diff --git a/packages/muelu/src/Graph/Containers/MueLu_Aggregates_def.hpp b/packages/muelu/src/Graph/Containers/MueLu_Aggregates_def.hpp
index 4ad46301f9df..7e5daf357256 100644
--- a/packages/muelu/src/Graph/Containers/MueLu_Aggregates_def.hpp
+++ b/packages/muelu/src/Graph/Containers/MueLu_Aggregates_def.hpp
@@ -191,12 +191,12 @@ namespace MueLu {
     for(LO i=0; i<numNodes; i++) {
       LO aggregate = vertex2AggId[i];
       if(aggregate !=INVALID) {
-	aggNodes[aggCurr[aggregate]] = i;
-	aggCurr[aggregate]++;
+        aggNodes[aggCurr[aggregate]] = i;
+        aggCurr[aggregate]++;
       }
       else {
-	unaggregated[currNumUnaggregated] = i;
-	currNumUnaggregated++;
+        unaggregated[currNumUnaggregated] = i;
+        currNumUnaggregated++;
       }
     }
     unaggregated.resize(currNumUnaggregated);
diff --git a/packages/muelu/src/Graph/Containers/MueLu_Aggregates_kokkos_decl.hpp b/packages/muelu/src/Graph/Containers/MueLu_Aggregates_kokkos_decl.hpp
index d1c5424b35ef..15cc165dfa0b 100644
--- a/packages/muelu/src/Graph/Containers/MueLu_Aggregates_kokkos_decl.hpp
+++ b/packages/muelu/src/Graph/Containers/MueLu_Aggregates_kokkos_decl.hpp
@@ -116,6 +116,7 @@ namespace MueLu {
     using node_type           = Kokkos::Compat::KokkosDeviceWrapperNode<DeviceType>;
     using device_type         = DeviceType;
     using range_type          = Kokkos::RangePolicy<local_ordinal_type, execution_space>;
+    using LO_view             = Kokkos::View<local_ordinal_type*, device_type>;
 
     using aggregates_sizes_type = Kokkos::View<LocalOrdinal*, device_type>;
 
@@ -259,6 +260,12 @@ namespace MueLu {
 
     local_graph_type GetGraph() const;
 
+    /*! @brief Generates a compressed list of nodes in each aggregate, where
+      the entries in aggNodes[aggPtr[i]] up to aggNodes[aggPtr[i+1]-1] contain the nodes in aggregate i.
+      unaggregated contains the list of nodes which are, for whatever reason, not aggregated (e.g. Dirichlet)
+     */
+    void ComputeNodesInAggregate(LO_view & aggPtr, LO_view & aggNodes, LO_view & unaggregated) const;
+
     //! @name Overridden from Teuchos::Describable
     //@{
 
diff --git a/packages/muelu/src/Graph/Containers/MueLu_Aggregates_kokkos_def.hpp b/packages/muelu/src/Graph/Containers/MueLu_Aggregates_kokkos_def.hpp
index 80827cb480e8..f8cba41cfaee 100644
--- a/packages/muelu/src/Graph/Containers/MueLu_Aggregates_kokkos_def.hpp
+++ b/packages/muelu/src/Graph/Containers/MueLu_Aggregates_kokkos_def.hpp
@@ -180,6 +180,58 @@ namespace MueLu {
 
     return graph_;
   }
+  
+  template <class LocalOrdinal, class GlobalOrdinal, class DeviceType>
+  void 
+  Aggregates_kokkos<LocalOrdinal, GlobalOrdinal, Kokkos::Compat::KokkosDeviceWrapperNode<DeviceType> >::ComputeNodesInAggregate(LO_view & aggPtr, LO_view & aggNodes, LO_view & unaggregated) const {
+    LO numAggs  = GetNumAggregates();
+    LO numNodes = vertex2AggId_->getLocalLength();
+    auto vertex2AggId = vertex2AggId_->getDeviceLocalView(Xpetra::Access::ReadOnly);
+    typename aggregates_sizes_type::const_type aggSizes = ComputeAggregateSizes(true);
+    LO INVALID = Teuchos::OrdinalTraits<LO>::invalid();
+
+    aggPtr = LO_view("aggPtr",numAggs+1);
+    aggNodes = LO_view("aggNodes",numNodes);
+    LO_view aggCurr("agg curr",numAggs+1);
+
+    // Construct the "rowptr" and the counter
+    Kokkos::parallel_scan("MueLu:Aggregates:ComputeNodesInAggregate:scan", range_type(0,numAggs+1),
+      KOKKOS_LAMBDA(const LO aggIdx, LO& aggOffset, bool final_pass) {
+        LO count = 0;
+        if(aggIdx < numAggs)
+          count = aggSizes(aggIdx);
+        if(final_pass) {
+          aggPtr(aggIdx) = aggOffset;
+          aggCurr(aggIdx) = aggOffset;
+          if(aggIdx==numAggs)
+            aggCurr(numAggs) = 0; // use this for counting unaggregated nodes
+        }
+        aggOffset += count;
+      });
+
+    // Preallocate unaggregated to the correct size
+    LO numUnaggregated = 0;
+    Kokkos::parallel_reduce("MueLu:Aggregates:ComputeNodesInAggregate:unaggregatedSize", range_type(0,numNodes),
+      KOKKOS_LAMBDA(const LO nodeIdx, LO & count) { 
+        if(vertex2AggId(nodeIdx,0)==INVALID) 
+          count++;
+      }, numUnaggregated);
+    unaggregated = LO_view("unaggregated",numUnaggregated);
+
+    // Stick the nodes in each aggregate's spot
+    Kokkos::parallel_for("MueLu:Aggregates:ComputeNodesInAggregate:for", range_type(0,numNodes),
+      KOKKOS_LAMBDA(const LO nodeIdx) {
+        LO aggIdx = vertex2AggId(nodeIdx,0);
+        if(aggIdx != INVALID) {
+          // atomic postincrement aggCurr(aggIdx) each time
+          aggNodes(Kokkos::atomic_fetch_add(&aggCurr(aggIdx),1)) = nodeIdx;
+        } else {
+          // same, but using last entry of aggCurr for unaggregated nodes
+          unaggregated(Kokkos::atomic_fetch_add(&aggCurr(numAggs),1)) = nodeIdx;
+        }
+      });
+    
+  }
 
   template <class LocalOrdinal, class GlobalOrdinal, class DeviceType>
   std::string Aggregates_kokkos<LocalOrdinal, GlobalOrdinal, Kokkos::Compat::KokkosDeviceWrapperNode<DeviceType> >::description() const {
diff --git a/packages/muelu/test/unit_tests_kokkos/Aggregates_kokkos.cpp b/packages/muelu/test/unit_tests_kokkos/Aggregates_kokkos.cpp
index 2d8deec90d7a..a9bb67efc595 100644
--- a/packages/muelu/test/unit_tests_kokkos/Aggregates_kokkos.cpp
+++ b/packages/muelu/test/unit_tests_kokkos/Aggregates_kokkos.cpp
@@ -611,6 +611,20 @@ namespace MueLuTests {
                             }, numBadAggregates);
     TEST_EQUALITY(numBadAggregates, 0);
 
+    // Check ComputeNodesInAggregate
+    typename Aggregates_kokkos::LO_view aggPtr, aggNodes, unaggregated;
+    aggregates->ComputeNodesInAggregate(aggPtr, aggNodes, unaggregated);
+    TEST_EQUALITY(aggPtr.extent_int(0), numAggs+1);
+    // TEST_EQUALITY(unaggregated.extent_int(0), 0); // 1 unaggregated node in the MPI_4 case
+    
+    // test aggPtr(i)+aggSizes(i)=aggPtr(i+1)
+    typename Aggregates_kokkos::LO_view::HostMirror aggPtr_h = Kokkos::create_mirror_view(aggPtr);
+    typename Aggregates_kokkos::aggregates_sizes_type::HostMirror aggSizes_h = Kokkos::create_mirror_view(aggSizes);
+    Kokkos::deep_copy(aggPtr_h, aggPtr);
+    Kokkos::deep_copy(aggSizes_h, aggSizes);
+    for(LO i=0; i<aggSizes_h.extent_int(0); ++i)
+      TEST_EQUALITY(aggPtr_h(i)+aggSizes_h(i), aggPtr_h(i+1));
+
   } //UncoupledPhase3
 
   TEUCHOS_UNIT_TEST_TEMPLATE_4_DECL(Aggregates_kokkos, AllowDroppingToCreateAdditionalDirichletRows, Scalar, LocalOrdinal, GlobalOrdinal, Node)