diff --git a/src/main/kotlin/gov/nist/secauto/oscal/tools/server/OscalCommandExecutor.kt b/src/main/kotlin/gov/nist/secauto/oscal/tools/server/OscalCommandExecutor.kt
index a31ab83..8d4d84f 100644
--- a/src/main/kotlin/gov/nist/secauto/oscal/tools/server/OscalCommandExecutor.kt
+++ b/src/main/kotlin/gov/nist/secauto/oscal/tools/server/OscalCommandExecutor.kt
@@ -30,6 +30,7 @@ import gov.nist.secauto.oscal.tools.cli.core.commands.ConvertCommand
 import gov.nist.secauto.oscal.tools.cli.core.commands.ValidateCommand
 import gov.nist.secauto.oscal.tools.cli.core.commands.ResolveCommand
 import gov.nist.secauto.oscal.tools.server.core.commands.QueryCommand
+import gov.nist.secauto.metaschema.cli.commands.ValidateModuleCommand
 
 open class OscalCommandExecutor(
     protected val command: String,
@@ -39,6 +40,7 @@ open class OscalCommandExecutor(
     protected val logger: Logger = LogManager.getLogger(this::class.java)
     protected open val commands: Map<String, () -> ICommand> = mapOf(
         "validate" to ::ValidateCommand,
+        "validate-metaschema" to ::ValidateModuleCommand,
         "convert" to ::ConvertCommand,
         "query" to ::QueryCommand,
         "resolve-profile" to ::ResolveCommand
diff --git a/src/main/kotlin/gov/nist/secauto/oscal/tools/server/OscalVerticle.kt b/src/main/kotlin/gov/nist/secauto/oscal/tools/server/OscalVerticle.kt
index 67a546b..73c3320 100644
--- a/src/main/kotlin/gov/nist/secauto/oscal/tools/server/OscalVerticle.kt
+++ b/src/main/kotlin/gov/nist/secauto/oscal/tools/server/OscalVerticle.kt
@@ -180,6 +180,7 @@ class OscalVerticle : CoroutineVerticle() {
                 val body = ctx.body().asString()
                 logger.info("Received body: $body")
                 val flags = ctx.queryParam("flags")
+                val encodedModule = ctx.queryParam("module").firstOrNull()
 
                 if (body.isNotEmpty()) {
                     // Create a temporary file
@@ -187,7 +188,14 @@ class OscalVerticle : CoroutineVerticle() {
 
                     val tempFilePath = tempFile.toAbsolutePath()
                     logger.info("Created temporary file: $tempFilePath")
-                    val args = mutableListOf("validate", tempFilePath.toString(),"--show-stack-trace")
+                    var command = "validate"
+                    encodedModule?.let { module ->
+                        if (module == "http://csrc.nist.gov/ns/oscal/metaschema/1.0") {
+                            command = "validate-metaschema"
+                        }
+                    }
+
+                    val args = mutableListOf(command, tempFilePath.toString(),"--show-stack-trace")
                     flags.forEach { flag ->
                         args.add(flagToParam(flag))
                     }    
@@ -238,11 +246,18 @@ class OscalVerticle : CoroutineVerticle() {
             try {
                 logger.info("Handling Validate request")
                 val encodedContent = ctx.queryParam("document").firstOrNull()
+                val encodedModule = ctx.queryParam("module").firstOrNull()
                 val constraint = ctx.queryParam("constraint")
                 val flags = ctx.queryParam("flags")
                 if (encodedContent != null) {
                     val content = processUrl(encodedContent)
-                    val args = mutableListOf("validate", content, "--show-stack-trace")
+                    var command = "validate"
+                    encodedModule?.let { module ->
+                        if (module == "http://csrc.nist.gov/ns/oscal/metaschema/1.0") {
+                            command = "validate-metaschema"
+                        }
+                    }
+                    val args = mutableListOf(command, content, "--show-stack-trace")
                     constraint.forEach { constraint_document ->
                         args.add("-c")
                         args.add(processUrl(constraint_document))
@@ -392,7 +407,7 @@ class OscalVerticle : CoroutineVerticle() {
                     }
                     mutableArgs.add("-o")    
                 }
-                if (mutableArgs[0] == "query"){
+                if (mutableArgs[0] == "query"||mutableArgs[0]=="validate-metaschema"){
                     mutableArgs.add("-o")    
                 }
                 mutableArgs.add(sarifFilePath)
diff --git a/src/main/resources/webroot/openapi.yaml b/src/main/resources/webroot/openapi.yaml
index 137fa98..af44036 100644
--- a/src/main/resources/webroot/openapi.yaml
+++ b/src/main/resources/webroot/openapi.yaml
@@ -42,6 +42,13 @@ paths:
           example: 
             - https://raw.githubusercontent.com/GSA/fedramp-automation/refs/heads/develop/src/validations/constraints/fedramp-external-constraints.xml
             - https://raw.githubusercontent.com/GSA/fedramp-automation/refs/heads/develop/src/validations/constraints/fedramp-external-constraints.xml
+        - in: query
+          name: module
+          required: false
+          schema:
+            type: string
+            enum: [http://csrc.nist.gov/ns/oscal/metaschema/1.0,http://csrc.nist.gov/ns/oscal/1.0]
+          description: URI or NS of metaschema module
         - in: query
           name: flags
           required: false
@@ -74,6 +81,13 @@ paths:
           example: 
             - https://raw.githubusercontent.com/GSA/fedramp-automation/refs/heads/develop/src/validations/constraints/fedramp-external-constraints.xml
             - https://raw.githubusercontent.com/GSA/fedramp-automation/refs/heads/develop/src/validations/constraints/fedramp-external-constraints.xml
+        - in: query
+          name: module
+          required: false
+          schema:
+            type: string
+            enum: [http://csrc.nist.gov/ns/oscal/metaschema/1.0,http://csrc.nist.gov/ns/oscal/1.0]
+          description: URI or NS of metaschema module
         - in: query
           name: flags
           required: false