diff --git a/converters/ontology/src/ossie_ontology/converter/ossie_to_spec/converter.py b/converters/ontology/src/ossie_ontology/converter/ossie_to_spec/converter.py
index b63bf9a47..c367285f5 100644
--- a/converters/ontology/src/ossie_ontology/converter/ossie_to_spec/converter.py
+++ b/converters/ontology/src/ossie_ontology/converter/ossie_to_spec/converter.py
@@ -79,6 +79,7 @@ def convert(model: OssieOntology) -> OssieSpec:
             requires=[f.raw_expr for f in ont.requires],
             ontology=_convert_ontology_concepts(ont),
             ontology_mappings=ontology_mappings,
+            prefixes=model.prefixes,
         )
 
 
@@ -117,6 +118,7 @@ def _convert_concept(concept: Concept, rels: list[Relationship]) -> ConceptCompo
         derived_by=[f.raw_expr for f in concept.derived_by],
         requires=[f.raw_expr for f in concept.requires],
         relationships=[_convert_relationship(rel) for rel in rels],
+        iri=concept.iri,
     )
 
 
@@ -135,6 +137,7 @@ def _convert_relationship(rel: Relationship) -> SpecRelationship:
         multiplicity=multiplicity,  # type: ignore[arg-type]
         derived_by=[f.raw_expr for f in rel.derived_by],
         requires=[f.raw_expr for f in rel.requires],
+        iri=rel.iri,
     )
 
 
diff --git a/converters/ontology/src/ossie_ontology/converter/spec_to_ossie/converter.py b/converters/ontology/src/ossie_ontology/converter/spec_to_ossie/converter.py
index 75992421b..776a2dcae 100644
--- a/converters/ontology/src/ossie_ontology/converter/spec_to_ossie/converter.py
+++ b/converters/ontology/src/ossie_ontology/converter/spec_to_ossie/converter.py
@@ -99,6 +99,7 @@ def convert(self, spec: OssieSpec) -> OssieOntology:
             description=spec.description,
             ai_context=spec.ai_context,
             version=spec.version,
+            prefixes=spec.prefixes,
         )
 
         self._populate_ontology(ontology, spec)
@@ -131,6 +132,7 @@ def _populate_ontology(self, ontology: OntologyComponent, spec: OssieSpec) -> No
                     type=ConceptType.from_value(concept_spec.type),
                     description=concept_spec.description,
                     extends=extends,
+                    iri=concept_spec.iri,
                 )
             )
 
@@ -219,6 +221,7 @@ def _convert_relationship(
             description=rel_spec.description,
             verbalizes=list(rel_spec.verbalizes) if rel_spec.verbalizes else None,
             multiplicity=multiplicity,
+            iri=rel_spec.iri,
         )
         ontology.add_relationship(relationship)
 
diff --git a/converters/ontology/src/ossie_ontology/model.py b/converters/ontology/src/ossie_ontology/model.py
index 21c722288..9badc8837 100644
--- a/converters/ontology/src/ossie_ontology/model.py
+++ b/converters/ontology/src/ossie_ontology/model.py
@@ -98,6 +98,7 @@ class Concept:
     _derived_by: list[Formula]
     _requires: list[Formula]
     _is_component: bool
+    _iri: str | None
 
     def __init__(
         self,
@@ -109,7 +110,8 @@ def __init__(
         identify_by: dict[str, Relationship] | None = None,
         derived_by: list[Formula] | None = None,
         requires: list[Formula] | None = None,
-        is_component: bool = True
+        is_component: bool = True,
+        iri: str | None = None,
     ):
         self._name = name
         self._type = type
@@ -120,6 +122,7 @@ def __init__(
         self._derived_by = derived_by if derived_by else []
         self._requires = requires if requires else []
         self._is_component = is_component
+        self._iri = iri
 
     def add_require(self, require: Formula) -> None:
         self._requires.append(require)
@@ -145,6 +148,10 @@ def type(self) -> ConceptType | None:
     def description(self) -> str | None:
         return self._description
 
+    @property
+    def iri(self) -> str | None:
+        return self._iri
+
     @property
     def is_builtin(self) -> bool:
         return self._builtin
@@ -207,6 +214,7 @@ class Relationship:
     _multiplicity: RelationshipMultiplicity | None
     _derived_by: list[Formula]
     _requires: list[Formula]
+    _iri: str | None
 
     def __init__(
         self,
@@ -216,6 +224,7 @@ def __init__(
         description: str | None = None,
         verbalizes: list[str] | None = None,
         multiplicity: RelationshipMultiplicity | None = None,
+        iri: str | None = None,
     ):
         self._name = name
         self._container = container
@@ -228,6 +237,7 @@ def __init__(
         self._verbalizations = parse_verbalizations(self, verbalizes)
         self._derived_by = []
         self._requires = []
+        self._iri = iri
 
     @property
     def name(self) -> str:
@@ -245,6 +255,10 @@ def container(self) -> Concept:
     def description(self) -> str | None:
         return self._description
 
+    @property
+    def iri(self) -> str | None:
+        return self._iri
+
     @property
     def signature(self) -> list[Concept]:
         return [role.player for role in self._roles]
@@ -1016,6 +1030,7 @@ class OssieOntology:
     _ontology: OntologyComponent
     _ontology_mappings: list[OntologyMapping]
     _ontology_mapping_index: dict[str, OntologyMapping]
+    _prefixes: dict[str, str]
 
     def __init__(
         self,
@@ -1024,6 +1039,7 @@ def __init__(
         description: str | None = None,
         ai_context: AiContext | None = None,
         version: str | None = None,
+        prefixes: dict[str, str] | None = None,
     ):
         self._name = name
         self._description = description
@@ -1032,6 +1048,7 @@ def __init__(
         self._ontology = ontology
         self._ontology_mappings = []
         self._ontology_mapping_index = {}
+        self._prefixes = dict(prefixes) if prefixes else {}
 
     @property
     def name(self) -> str:
@@ -1063,6 +1080,11 @@ def add_ontology_mapping(self, mapping: OntologyMapping) -> None:
     def ontology_mappings(self) -> list[OntologyMapping]:
         return list(self._ontology_mappings)
 
+    @property
+    def prefixes(self) -> dict[str, str]:
+        """Namespace prefixes the document's QName `iri` values resolve against."""
+        return dict(self._prefixes)
+
 
 # ---------------------------------------------------------------------------
 # Verbalization parser (handles a list of verbalization patterns)
diff --git a/converters/ontology/src/ossie_ontology/spec.py b/converters/ontology/src/ossie_ontology/spec.py
index f2a59012f..637495c96 100644
--- a/converters/ontology/src/ossie_ontology/spec.py
+++ b/converters/ontology/src/ossie_ontology/spec.py
@@ -72,6 +72,7 @@ class Relationship(OssieObject):
     """
     name: str
     description: str | None = None
+    iri: str | None = None
     roles: list[Role] = Field(default_factory=list)
     verbalizes: list[str] = Field(default_factory=list)
     multiplicity: Literal["OneToOne", "ManyToOne"] | None = None
@@ -100,6 +101,7 @@ class ConceptComponent(OssieObject):
     concept: str
     type: Literal["EntityType", "ValueType"] | None = None
     description: str | None = None
+    iri: str | None = None
     extends: list[str] | None = None
     identify_by: list[str] = Field(default_factory=list)
     derived_by: list[str] = Field(default_factory=list)
@@ -243,6 +245,7 @@ class OssieSpec(OssieObject):
     version: str | None = None
     name: str
     description: str | None = None
+    prefixes: dict[str, str] = Field(default_factory=dict)
     requires: list[str] = Field(default_factory=list)
     ai_context: AiContext | None = None
     ontology: list[ConceptComponent] = Field(default_factory=list)
diff --git a/converters/ontology/tests/test_ossie_parser.py b/converters/ontology/tests/test_ossie_parser.py
index d23808a2e..91b1976f2 100644
--- a/converters/ontology/tests/test_ossie_parser.py
+++ b/converters/ontology/tests/test_ossie_parser.py
@@ -356,3 +356,68 @@ def test_relationships_are_grouped_under_their_own_container():
         "Alpha": ["a1", "a2"],
         "Beta": ["b1", "b2"],
     }
+
+
+# ----- Global identifiers -----------------------------------------------
+
+_IRI_SPEC = {
+    "version": "0.2.0.dev0",
+    "name": "Demo",
+    "prefixes": {"foaf": "http://xmlns.com/foaf/0.1/"},
+    "ontology": [
+        {
+            "concept": "Person",
+            "type": "EntityType",
+            "iri": "foaf:Person",
+            "identify_by": ["person_name"],
+            "relationships": [
+                {
+                    "name": "person_name",
+                    "iri": "foaf:name",
+                    "roles": [{"concept": "String"}],
+                    "verbalizes": ["{Person} is identified by {String}"],
+                    "multiplicity": "OneToOne",
+                }
+            ],
+        }
+    ],
+}
+
+
+def test_iri_and_prefixes_survive_a_round_trip(tmp_path: Path):
+    """A document that pins its concepts to an external vocabulary must come
+    back out carrying the same pins.
+
+    `iri` and `prefixes` are what tie an Ossie ontology to RDF/OWL vocabularies,
+    so dropping them silently turns a mapped ontology into an unmapped one.
+    """
+    path = tmp_path / "spec.yaml"
+    path.write_text(yaml.safe_dump(_IRI_SPEC))
+
+    model = OssieParser().parse(path)
+
+    assert model.prefixes == {"foaf": "http://xmlns.com/foaf/0.1/"}
+    person = model.ontology.lookup_concept("Person")
+    assert person is not None
+    assert person.iri == "foaf:Person"
+    assert model.ontology.lookup_concept_relationship(person, "person_name").iri == "foaf:name"
+
+    roundtrip_path = tmp_path / "roundtrip.yaml"
+    roundtrip_path.write_text(OssieToSpecConverter.convert(model).dump_yaml())
+    reparsed = OssieParser().parse(roundtrip_path)
+
+    assert reparsed.prefixes == model.prefixes
+    reparsed_person = reparsed.ontology.lookup_concept("Person")
+    assert reparsed_person.iri == "foaf:Person"
+    assert reparsed.ontology.lookup_concept_relationship(reparsed_person, "person_name").iri == "foaf:name"
+
+
+def test_a_document_without_iris_dumps_neither_field(tmp_path: Path):
+    """Both fields are optional, so a document that declares neither must dump
+    exactly as it did before they existed."""
+    path = _write_spec(tmp_path, [_concept("Gadget")])
+
+    dumped = OssieToSpecConverter.convert(OssieParser().parse(path)).dump_yaml()
+
+    assert "iri:" not in dumped
+    assert "prefixes:" not in dumped