diff --git a/src/scp_sdk/__init__.py b/src/scp_sdk/__init__.py
index 714f32b..cfa203e 100644
--- a/src/scp_sdk/__init__.py
+++ b/src/scp_sdk/__init__.py
@@ -37,6 +37,12 @@
     IntegrationResult,
 )
 
+# Utilities
+from .utils import TierUtils
+
+# Testing utilities
+from .testing import GraphFixture, ManifestFixture
+
 __all__ = [
     "__version__",
     # Models
@@ -67,4 +73,9 @@
     "IntegrationConfig",
     "IntegrationValidator",
     "IntegrationResult",
+    # Utilities
+    "TierUtils",
+    # Testing
+    "GraphFixture",
+    "ManifestFixture",
 ]
diff --git a/src/scp_sdk/testing/__init__.py b/src/scp_sdk/testing/__init__.py
new file mode 100644
index 0000000..16c2eda
--- /dev/null
+++ b/src/scp_sdk/testing/__init__.py
@@ -0,0 +1,5 @@
+"""Testing utilities for SCP SDK."""
+
+from .fixtures import GraphFixture, ManifestFixture
+
+__all__ = ["GraphFixture", "ManifestFixture"]
diff --git a/src/scp_sdk/testing/fixtures.py b/src/scp_sdk/testing/fixtures.py
new file mode 100644
index 0000000..f392390
--- /dev/null
+++ b/src/scp_sdk/testing/fixtures.py
@@ -0,0 +1,184 @@
+"""Test fixtures for SCP SDK testing.
+
+Provides convenient factory methods for creating test graphs and manifests,
+reducing boilerplate in integration tests.
+"""
+
+from typing import Literal
+
+from ..core.graph import Graph, SystemNode, DependencyEdge
+from ..core.models import (
+    SCPManifest,
+    System,
+    Ownership,
+    Contact,
+    Capability,
+    Dependency,
+    Classification,
+)
+
+
+class GraphFixture:
+    """Factory for test graphs.
+
+    Example:
+        >>> graph = GraphFixture.simple_graph()
+        >>> assert len(graph) == 1
+        >>>
+        >>> graph = GraphFixture.with_dependencies(3)
+        >>> assert len(list(graph.dependencies())) > 0
+    """
+
+    @staticmethod
+    def simple_graph() -> Graph:
+        """Create minimal valid graph for testing.
+
+        Returns:
+            Graph with single system, no dependencies
+        """
+        system = SystemNode(urn="urn:scp:test:service-a", name="Test Service A")
+        return Graph(systems=[system], edges=[])
+
+    @staticmethod
+    def with_dependencies(num_systems: int = 3) -> Graph:
+        """Create graph with dependency edges.
+
+        Creates a chain: system-a -> system-b -> system-c
+
+        Args:
+            num_systems: Number of systems to create (minimum 2)
+
+        Returns:
+            Graph with systems and dependency edges
+        """
+        if num_systems < 2:
+            num_systems = 2
+
+        systems = []
+        edges = []
+
+        for i in range(num_systems):
+            urn = f"urn:scp:test:service-{chr(ord('a') + i)}"
+            name = f"Test Service {chr(ord('A') + i)}"
+            systems.append(SystemNode(urn=urn, name=name, tier=i % 5 + 1))
+
+            # Create edge to next system (except for last)
+            if i < num_systems - 1:
+                next_urn = f"urn:scp:test:service-{chr(ord('a') + i + 1)}"
+                edges.append(DependencyEdge(from_urn=urn, to_urn=next_urn))
+
+        return Graph(systems=systems, edges=edges)
+
+    @staticmethod
+    def invalid_graph(
+        issue: Literal[
+            "missing_name", "broken_dependency", "orphaned"
+        ] = "missing_name",
+    ) -> Graph:
+        """Create graph with specific validation issue.
+
+        Args:
+            issue: Type of validation issue to create
+
+        Returns:
+            Graph with specified validation issue
+        """
+        if issue == "missing_name":
+            system = SystemNode(urn="urn:scp:test:invalid", name="")
+            return Graph(systems=[system], edges=[])
+
+        elif issue == "broken_dependency":
+            system = SystemNode(urn="urn:scp:test:service-a", name="Service A")
+            edge = DependencyEdge(
+                from_urn="urn:scp:test:service-a", to_urn="urn:scp:test:missing"
+            )
+            return Graph(systems=[system], edges=[edge])
+
+        elif issue == "orphaned":
+            system = SystemNode(urn="urn:scp:test:orphan", name="Orphaned System")
+            return Graph(systems=[system], edges=[])
+
+        return GraphFixture.simple_graph()
+
+
+class ManifestFixture:
+    """Factory for test manifests.
+
+    Example:
+        >>> manifest = ManifestFixture.minimal()
+        >>> assert manifest.system.name is not None
+        >>>
+        >>> manifest = ManifestFixture.full_featured()
+        >>> assert manifest.ownership is not None
+    """
+
+    @staticmethod
+    def minimal() -> SCPManifest:
+        """Minimal valid manifest.
+
+        Returns:
+            Manifest with only required fields
+        """
+        return SCPManifest(
+            scp="0.1.0",
+            system=System(urn="urn:scp:test:minimal", name="Minimal Service"),
+        )
+
+    @staticmethod
+    def full_featured() -> SCPManifest:
+        """Manifest with all optional fields.
+
+        Returns:
+            Manifest with classification, ownership, capabilities, dependencies
+        """
+        return SCPManifest(
+            scp="0.1.0",
+            system=System(
+                urn="urn:scp:test:full",
+                name="Full Featured Service",
+                description="A test service with all features",
+                classification=Classification(
+                    tier=2, domain="test", tags=["api", "backend"]
+                ),
+            ),
+            ownership=Ownership(
+                team="platform-team",
+                contacts=[
+                    Contact(type="email", ref="team@example.com"),
+                    Contact(type="slack", ref="#platform"),
+                ],
+                escalation=["lead", "manager", "director"],
+            ),
+            provides=[
+                Capability(capability="user-api", type="rest"),  # type: ignore[call-arg]
+                Capability(capability="user-events", type="event"),  # type: ignore[call-arg]
+            ],
+            depends=[
+                Dependency(
+                    system="urn:scp:test:database",
+                    capability="user-data",
+                    type="data",
+                    criticality="required",
+                    failure_mode="fail-fast",
+                )
+            ],
+        )
+
+    @staticmethod
+    def with_tier(tier: int) -> SCPManifest:
+        """Create manifest with specific tier.
+
+        Args:
+            tier: Tier value (1-5)
+
+        Returns:
+            Manifest with specified tier
+        """
+        return SCPManifest(
+            scp="0.1.0",
+            system=System(
+                urn=f"urn:scp:test:tier-{tier}",
+                name=f"Tier {tier} Service",
+                classification=Classification(tier=tier),
+            ),
+        )
diff --git a/src/scp_sdk/utils/__init__.py b/src/scp_sdk/utils/__init__.py
new file mode 100644
index 0000000..9539284
--- /dev/null
+++ b/src/scp_sdk/utils/__init__.py
@@ -0,0 +1,5 @@
+"""SDK utilities."""
+
+from .tier import TierUtils
+
+__all__ = ["TierUtils"]
diff --git a/src/scp_sdk/utils/tier.py b/src/scp_sdk/utils/tier.py
new file mode 100644
index 0000000..cd26d99
--- /dev/null
+++ b/src/scp_sdk/utils/tier.py
@@ -0,0 +1,93 @@
+"""Utilities for working with tier classifications.
+
+Tier is a core SCP concept (1-5 scale for criticality). These utilities provide
+standardized tier handling and mapping support for integrations.
+"""
+
+from typing import Any
+
+
+class TierUtils:
+    """Utilities for working with tier classifications.
+
+    Tier scale (1-5):
+    - 1: Critical (highest priority, mission-critical)
+    - 2: High (important production systems)
+    - 3: Medium (standard production systems)
+    - 4: Low (non-critical systems)
+    - 5: Planning (experimental/development)
+    """
+
+    TIER_NAMES = {
+        1: "Critical",
+        2: "High",
+        3: "Medium",
+        4: "Low",
+        5: "Planning",
+    }
+
+    @staticmethod
+    def get_name(tier: int | None) -> str:
+        """Get human-readable tier name.
+
+        Args:
+            tier: Tier value (1-5) or None
+
+        Returns:
+            Tier name or "Unknown" if invalid
+
+        Example:
+            >>> TierUtils.get_name(1)
+            'Critical'
+            >>> TierUtils.get_name(None)
+            'Unknown'
+        """
+        if tier is None:
+            return "Unknown"
+        return TierUtils.TIER_NAMES.get(tier, "Unknown")
+
+    @staticmethod
+    def validate_tier(tier: int | None) -> bool:
+        """Check if tier value is valid.
+
+        Args:
+            tier: Tier value to validate
+
+        Returns:
+            True if valid (1-5) or None, False otherwise
+
+        Example:
+            >>> TierUtils.validate_tier(3)
+            True
+            >>> TierUtils.validate_tier(10)
+            False
+        """
+        return tier is None or (isinstance(tier, int) and 1 <= tier <= 5)
+
+    @staticmethod
+    def map_tier(
+        tier: int | None, mapping: dict[int, Any], default: Any = "Medium"
+    ) -> Any:
+        """Map tier to custom value with fallback.
+
+        Useful for integrations that need to map SCP tiers to vendor-specific
+        values (e.g., ServiceNow criticality strings).
+
+        Args:
+            tier: SCP tier value
+            mapping: Custom tier mapping dictionary
+            default: Default value if tier not in mapping
+
+        Returns:
+            Mapped value or default
+
+        Example:
+            >>> mapping = {1: "P0", 2: "P1", 3: "P2"}
+            >>> TierUtils.map_tier(1, mapping)
+            'P0'
+            >>> TierUtils.map_tier(None, mapping, default="P3")
+            'P3'
+        """
+        if tier is None:
+            return default
+        return mapping.get(tier, default)
diff --git a/tests/test_fixtures.py b/tests/test_fixtures.py
new file mode 100644
index 0000000..39ee4aa
--- /dev/null
+++ b/tests/test_fixtures.py
@@ -0,0 +1,84 @@
+"""Tests for testing fixtures."""
+
+from scp_sdk import GraphFixture, ManifestFixture, Graph, SCPManifest
+
+
+class TestGraphFixture:
+    """Tests for GraphFixture class."""
+
+    def test_simple_graph(self):
+        """Should create minimal valid graph."""
+        graph = GraphFixture.simple_graph()
+        assert isinstance(graph, Graph)
+        assert len(graph) == 1
+        assert len(list(graph.dependencies())) == 0
+
+    def test_with_dependencies_default(self):
+        """Should create graph with 3 systems by default."""
+        graph = GraphFixture.with_dependencies()
+        assert len(graph) == 3
+        assert len(list(graph.dependencies())) == 2  # Chain: a->b->c
+
+    def test_with_dependencies_custom_count(self):
+        """Should create graph with specified number of systems."""
+        graph = GraphFixture.with_dependencies(5)
+        assert len(graph) == 5
+        assert len(list(graph.dependencies())) == 4  # Chain: a->b->c->d->e
+
+    def test_with_dependencies_minimum_enforced(self):
+        """Should enforce minimum of 2 systems."""
+        graph = GraphFixture.with_dependencies(1)
+        assert len(graph) >= 2
+
+    def test_invalid_graph_missing_name(self):
+        """Should create graph with missing name issue."""
+        graph = GraphFixture.invalid_graph("missing_name")
+        issues = graph.validate()
+        # Should have orphaned system (info) but name validation is integration-specific
+        assert isinstance(issues, list)
+
+    def test_invalid_graph_broken_dependency(self):
+        """Should create graph with broken dependency."""
+        graph = GraphFixture.invalid_graph("broken_dependency")
+        issues = graph.validate()
+        # Should have warning about missing dependency target
+        warnings = [i for i in issues if i.severity == "warning"]
+        assert len(warnings) > 0
+
+    def test_invalid_graph_orphaned(self):
+        """Should create graph with orphaned system."""
+        graph = GraphFixture.invalid_graph("orphaned")
+        issues = graph.validate()
+        # Should have info about orphaned system
+        infos = [i for i in issues if i.severity == "info"]
+        assert len(infos) > 0
+
+
+class TestManifestFixture:
+    """Tests for ManifestFixture class."""
+
+    def test_minimal(self):
+        """Should create minimal valid manifest."""
+        manifest = ManifestFixture.minimal()
+        assert isinstance(manifest, SCPManifest)
+        assert manifest.system.name is not None
+        assert manifest.ownership is None
+        assert manifest.provides is None
+        assert manifest.depends is None
+
+    def test_full_featured(self):
+        """Should create manifest with all optional fields."""
+        manifest = ManifestFixture.full_featured()
+        assert isinstance(manifest, SCPManifest)
+        assert manifest.system.classification is not None
+        assert manifest.ownership is not None
+        assert manifest.provides is not None
+        assert manifest.depends is not None
+        assert len(manifest.provides) > 0
+        assert len(manifest.depends) > 0
+
+    def test_with_tier(self):
+        """Should create manifest with specified tier."""
+        for tier in [1, 2, 3, 4, 5]:
+            manifest = ManifestFixture.with_tier(tier)
+            assert manifest.system.classification.tier == tier
diff --git a/tests/test_tier.py b/tests/test_tier.py
new file mode 100644
index 0000000..7523c54
--- /dev/null
+++ b/tests/test_tier.py
@@ -0,0 +1,73 @@
+"""Tests for tier utilities."""
+
+from scp_sdk import TierUtils
+
+
+class TestTierUtils:
+    """Tests for TierUtils class."""
+
+    def test_tier_names(self):
+        """Should have correct tier name mappings."""
+        assert TierUtils.TIER_NAMES[1] == "Critical"
+        assert TierUtils.TIER_NAMES[2] == "High"
+        assert TierUtils.TIER_NAMES[3] == "Medium"
+        assert TierUtils.TIER_NAMES[4] == "Low"
+        assert TierUtils.TIER_NAMES[5] == "Planning"
+
+    def test_get_name_valid(self):
+        """Should return correct names for valid tiers."""
+        assert TierUtils.get_name(1) == "Critical"
+        assert TierUtils.get_name(3) == "Medium"
+        assert TierUtils.get_name(5) == "Planning"
+
+    def test_get_name_none(self):
+        """Should return Unknown for None."""
+        assert TierUtils.get_name(None) == "Unknown"
+
+    def test_get_name_invalid(self):
+        """Should return Unknown for invalid tiers."""
+        assert TierUtils.get_name(0) == "Unknown"
+        assert TierUtils.get_name(10) == "Unknown"
+        assert TierUtils.get_name(-1) == "Unknown"
+
+    def test_validate_tier_valid(self):
+        """Should validate correct tier values."""
+        assert TierUtils.validate_tier(1) is True
+        assert TierUtils.validate_tier(3) is True
+        assert TierUtils.validate_tier(5) is True
+
+    def test_validate_tier_none(self):
+        """Should accept None as valid."""
+        assert TierUtils.validate_tier(None) is True
+
+    def test_validate_tier_invalid(self):
+        """Should reject invalid tier values."""
+        assert TierUtils.validate_tier(0) is False
+        assert TierUtils.validate_tier(6) is False
+        assert TierUtils.validate_tier(10) is False
+        assert TierUtils.validate_tier(-1) is False
+
+    def test_map_tier_with_mapping(self):
+        """Should map tier using custom mapping."""
+        mapping = {1: "P0", 2: "P1", 3: "P2"}
+        assert TierUtils.map_tier(1, mapping) == "P0"
+        assert TierUtils.map_tier(2, mapping) == "P1"
+        assert TierUtils.map_tier(3, mapping) == "P2"
+
+    def test_map_tier_default(self):
+        """Should use default for unmapped tiers."""
+        mapping = {1: "P0", 2: "P1"}
+        assert TierUtils.map_tier(3, mapping, default="P3") == "P3"
+        assert TierUtils.map_tier(None, mapping, default="P3") == "P3"
+
+    def test_map_tier_servicenow_pattern(self):
+        """Should work with ServiceNow-style criticality mapping."""
+        mapping = {
+            1: "1 - Critical",
+            2: "2 - High",
+            3: "3 - Medium",
+            4: "4 - Low",
+            5: "5 - Planning",
+        }
+        assert TierUtils.map_tier(1, mapping) == "1 - Critical"
+        assert TierUtils.map_tier(3, mapping) == "3 - Medium"