diff --git a/Sources/XKit/DeveloperServices/App Groups/DeveloperServicesAssignAppGroupRequest.swift b/Sources/XKit/DeveloperServices/App Groups/DeveloperServicesAssignAppGroupRequest.swift
index 713afdb0..399ed8c6 100644
--- a/Sources/XKit/DeveloperServices/App Groups/DeveloperServicesAssignAppGroupRequest.swift	
+++ b/Sources/XKit/DeveloperServices/App Groups/DeveloperServicesAssignAppGroupRequest.swift	
@@ -8,6 +8,9 @@
 
 import Foundation
 
+/// Assigns a set of app groups to an App ID. The request replaces the App ID's groups with
+/// `groupIDs`, so every group the app needs has to be in one request: assigning them one
+/// request at a time leaves only the last one standing.
 public final class DeveloperServicesAssignAppGroupRequest: DeveloperServicesPlatformRequest {
 
     public struct Response: Decodable, Sendable {}
@@ -16,14 +19,14 @@ public final class DeveloperServicesAssignAppGroupRequest: DeveloperServicesPlat
     public let platform: DeveloperServicesPlatform
     public let teamID: DeveloperServicesTeam.ID
     public let appIDID: String
-    public let groupID: DeveloperServicesAppGroup.ID
+    public let groupIDs: [DeveloperServicesAppGroup.ID]
 
     var subAction: String { return "assignApplicationGroupToAppId" }
     var subParameters: [String: Any] {
         return [
             "teamId": teamID.rawValue,
             "appIdId": appIDID,
-            "applicationGroups": groupID.rawValue
+            "applicationGroups": groupIDs.map(\.rawValue)
         ]
     }
 
@@ -31,12 +34,12 @@ public final class DeveloperServicesAssignAppGroupRequest: DeveloperServicesPlat
         platform: DeveloperServicesPlatform,
         teamID: DeveloperServicesTeam.ID,
         appIDID: String,
-        groupID: DeveloperServicesAppGroup.ID
+        groupIDs: [DeveloperServicesAppGroup.ID]
     ) {
         self.platform = platform
         self.teamID = teamID
         self.appIDID = appIDID
-        self.groupID = groupID
+        self.groupIDs = groupIDs
     }
 
 }
diff --git a/Sources/XKit/DeveloperServices/App Groups/DeveloperServicesAssignAppGroupsOperation.swift b/Sources/XKit/DeveloperServices/App Groups/DeveloperServicesAssignAppGroupsOperation.swift
index b13e1a5b..d10fa846 100644
--- a/Sources/XKit/DeveloperServices/App Groups/DeveloperServicesAssignAppGroupsOperation.swift	
+++ b/Sources/XKit/DeveloperServices/App Groups/DeveloperServicesAssignAppGroupsOperation.swift	
@@ -33,52 +33,60 @@ public struct DeveloperServicesAssignAppGroupsOperation: DeveloperServicesOperat
         self.client = DeveloperServicesClient(authData: authData)
     }
 
+    /// Finds the team's group for `groupID`, creating it when there is none.
     private func upsertAppGroup(
         _ groupID: DeveloperServicesAppGroup.GroupID,
         existingGroups: [String: DeveloperServicesAppGroup]
-    ) async throws -> DeveloperServicesAppGroup.GroupID {
+    ) async throws -> DeveloperServicesAppGroup {
         let sanitized = ProvisioningIdentifiers.sanitize(groupID: groupID)
-        let group: DeveloperServicesAppGroup
         if let existingGroup = existingGroups[sanitized] {
-            group = existingGroup
-        } else {
-            let groupID = ProvisioningIdentifiers.groupID(fromSanitized: sanitized, context: context)
-            let name = ProvisioningIdentifiers.groupName(fromSanitized: sanitized)
-            let request = DeveloperServicesAddAppGroupRequest(
-                platform: .iOS,
-                teamID: xcodeAuthData.teamID,
-                name: name,
-                groupID: groupID
-            )
-            group = try await client.send(request)
+            return existingGroup
         }
-
-        _ = try await client.send(
-            DeveloperServicesAssignAppGroupRequest(
-                platform: .iOS,
-                teamID: xcodeAuthData.teamID,
-                appIDID: appID.id,
-                groupID: group.id
-            )
+        let groupID = ProvisioningIdentifiers.groupID(fromSanitized: sanitized, context: context)
+        let name = ProvisioningIdentifiers.groupName(fromSanitized: sanitized)
+        let request = DeveloperServicesAddAppGroupRequest(
+            platform: .iOS,
+            teamID: xcodeAuthData.teamID,
+            name: name,
+            groupID: groupID
         )
-
-        return group.groupID
+        return try await client.send(request)
     }
 
+    /// Creates any missing groups, then assigns all of them to the App ID in one request.
+    /// `assignApplicationGroupToAppId` replaces the App ID's groups with the ones in the request,
+    /// so assigning each group separately (as this once did, concurrently) left the App ID with
+    /// only one of them, and an app with two groups got a profile that iOS refused to install.
+    /// Returns the groups' IDs in the order they were given.
     public func perform() async throws -> [DeveloperServicesAppGroup.GroupID] {
         let existing = try await client.send(DeveloperServicesListAppGroupsRequest(
             platform: .iOS, teamID: xcodeAuthData.teamID
         ))
         let sanitized = existing.map { (ProvisioningIdentifiers.sanitize(groupID: $0.groupID), $0) }
         let dict = Dictionary(sanitized, uniquingKeysWith: { $1 })
-        return try await withThrowingTaskGroup(of: DeveloperServicesAppGroup.GroupID.self) { group in
-            for groupID in groupIDs {
+        let groups = try await withThrowingTaskGroup(of: (Int, DeveloperServicesAppGroup).self) { group in
+            for (index, groupID) in groupIDs.enumerated() {
                 group.addTask {
-                    try await upsertAppGroup(groupID, existingGroups: dict)
+                    (index, try await upsertAppGroup(groupID, existingGroups: dict))
                 }
             }
             return try await group.reduce(into: []) { $0.append($1) }
         }
+        .sorted { $0.0 < $1.0 }
+        .map(\.1)
+
+        if !groups.isEmpty {
+            _ = try await client.send(
+                DeveloperServicesAssignAppGroupRequest(
+                    platform: .iOS,
+                    teamID: xcodeAuthData.teamID,
+                    appIDID: appID.id,
+                    groupIDs: groups.map(\.id)
+                )
+            )
+        }
+
+        return groups.map(\.groupID)
     }
 
 }