diff --git a/changes/838.feature.rst b/changes/838.feature.rst
new file mode 100644
index 00000000..850da7ab
--- /dev/null
+++ b/changes/838.feature.rst
@@ -0,0 +1 @@
+Add the SSC MSOS Level 4 detection efficiency catalog schema.
diff --git a/latest/SSC/MSOS/keywords/msos_detection_efficiency.yaml b/latest/SSC/MSOS/keywords/msos_detection_efficiency.yaml
new file mode 100644
index 00000000..2255aa7b
--- /dev/null
+++ b/latest/SSC/MSOS/keywords/msos_detection_efficiency.yaml
@@ -0,0 +1,55 @@
+%YAML 1.1
+---
+$schema: asdf://stsci.edu/datamodels/roman/schemas/rad_schema-2.0.0
+id: asdf://stsci.edu/datamodels/roman/schemas/SSC/MSOS/keywords/msos_detection_efficiency-1.0.0
+
+title: MSOS detection efficiency keywords
+extName: SSC
+type: object
+properties:
+  inject_medium:
+    title: Injection Medium
+    description: Detection efficiency injection medium represented by the rows in this file.
+    type: string
+    maxLength: 16
+    enum:
+      - images
+      - lightcurve
+      - rhie
+    archive_catalog:
+      datatype: nvarchar(16)
+      destination: [WFIMSOSCatalog.inject_medium]
+  tp_count:
+    title: True Positive Count
+    description: Number of rows in this file with BinaryClass equal to TP.
+    type: integer
+    minimum: 0
+    archive_catalog:
+      datatype: int
+      destination: [WFIMSOSCatalog.tp_count]
+  fp_count:
+    title: False Positive Count
+    description: Number of rows in this file with BinaryClass equal to FP.
+    type: integer
+    minimum: 0
+    archive_catalog:
+      datatype: int
+      destination: [WFIMSOSCatalog.fp_count]
+  tn_count:
+    title: True Negative Count
+    description: Number of rows in this file with BinaryClass equal to TN.
+    type: integer
+    minimum: 0
+    archive_catalog:
+      datatype: int
+      destination: [WFIMSOSCatalog.tn_count]
+  fn_count:
+    title: False Negative Count
+    description: Number of rows in this file with BinaryClass equal to FN.
+    type: integer
+    minimum: 0
+    archive_catalog:
+      datatype: int
+      destination: [WFIMSOSCatalog.fn_count]
+
+required: [inject_medium, tp_count, fp_count, tn_count, fn_count]
diff --git a/latest/SSC/MSOS/wfi_microlensing_detection_efficiency_catalog_level_4.yaml b/latest/SSC/MSOS/wfi_microlensing_detection_efficiency_catalog_level_4.yaml
new file mode 100644
index 00000000..d3cf7251
--- /dev/null
+++ b/latest/SSC/MSOS/wfi_microlensing_detection_efficiency_catalog_level_4.yaml
@@ -0,0 +1,13 @@
+%YAML 1.1
+---
+$schema: asdf://stsci.edu/datamodels/roman/schemas/rad_schema-2.0.0
+id: asdf://stsci.edu/datamodels/roman/schemas/SSC/MSOS/wfi_microlensing_detection_efficiency_catalog_level_4-1.0.0
+
+title: GBTDS Level 4 Microlensing Detection Efficiency Catalog
+archive_meta: Science WFI Level 4 MSOS Detection Efficiency Catalog
+type: object
+allOf:
+  - $ref: asdf://stsci.edu/datamodels/roman/schemas/SSC/ssc_basic-1.0.0
+  - $ref: asdf://stsci.edu/datamodels/roman/schemas/SSC/MSOS/keywords/msos_basic-1.0.0
+  - $ref: asdf://stsci.edu/datamodels/roman/schemas/SSC/MSOS/keywords/msos_common-1.0.0
+  - $ref: asdf://stsci.edu/datamodels/roman/schemas/SSC/MSOS/keywords/msos_detection_efficiency-1.0.0
diff --git a/pyproject.toml b/pyproject.toml
index 1df1fd17..ce4c456a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -100,6 +100,7 @@ asdf_schema_xfail_tests = [
   "latest/SSC/GDPS/wfi_spec_dqa_2d_level_4.yaml",
   "latest/SSC/GDPS/wfi_spec_catalog_dqa_level_4.yaml",
   "latest/SSC/MSOS/wfi_microlensing_event_catalog_level_4.yaml",
+  "latest/SSC/MSOS/wfi_microlensing_detection_efficiency_catalog_level_4.yaml",
   "latest/SSC/MSOS/wfi_microlensing_light_curve_catalog_level_4.yaml",
   "latest/SSC/MSOS/wfi_microlensing_object_periodic_catalog_level_4.yaml",
   "latest/SSC/MSOS/wfi_microlensing_object_fiducial_catalog_level_4.yaml",
diff --git a/src/rad/resources/schemas/SSC/MSOS/keywords/msos_detection_efficiency-1.0.0.yaml b/src/rad/resources/schemas/SSC/MSOS/keywords/msos_detection_efficiency-1.0.0.yaml
new file mode 120000
index 00000000..baaa18df
--- /dev/null
+++ b/src/rad/resources/schemas/SSC/MSOS/keywords/msos_detection_efficiency-1.0.0.yaml
@@ -0,0 +1 @@
+../../../../../../../latest/SSC/MSOS/keywords/msos_detection_efficiency.yaml
\ No newline at end of file
diff --git a/src/rad/resources/schemas/SSC/MSOS/wfi_microlensing_detection_efficiency_catalog_level_4-1.0.0.yaml b/src/rad/resources/schemas/SSC/MSOS/wfi_microlensing_detection_efficiency_catalog_level_4-1.0.0.yaml
new file mode 120000
index 00000000..b3542bb5
--- /dev/null
+++ b/src/rad/resources/schemas/SSC/MSOS/wfi_microlensing_detection_efficiency_catalog_level_4-1.0.0.yaml
@@ -0,0 +1 @@
+../../../../../../latest/SSC/MSOS/wfi_microlensing_detection_efficiency_catalog_level_4.yaml
\ No newline at end of file