diff --git a/interface/src/avatar/SkeletonModel.cpp b/interface/src/avatar/SkeletonModel.cpp
index ffe711b03b..536f957143 100644
--- a/interface/src/avatar/SkeletonModel.cpp
+++ b/interface/src/avatar/SkeletonModel.cpp
@@ -14,14 +14,11 @@
 
 #include <VerletCapsuleShape.h>
 #include <VerletSphereShape.h>
-#include <DistanceConstraint.h>
-#include <FixedConstraint.h>
 
 #include "Application.h"
 #include "Avatar.h"
 #include "Hand.h"
 #include "Menu.h"
-#include "MuscleConstraint.h"
 #include "SkeletonModel.h"
 #include "SkeletonRagdoll.h"
 
@@ -606,6 +603,7 @@ void SkeletonModel::buildShapes() {
 
     float uniformScale = extractUniformScale(_scale);
     const int numStates = _jointStates.size();
+    float totalMass = 0.0f;
     for (int i = 0; i < numStates; i++) {
         JointState& state = _jointStates[i];
         const FBXJoint& joint = state.getFBXJoint();
@@ -624,26 +622,31 @@ void SkeletonModel::buildShapes() {
         if (type == Shape::SPHERE_SHAPE) {
             shape = new VerletSphereShape(radius, &(points[i]));
             shape->setEntity(this);
-            points[i].setMass(massScale * glm::max(MIN_JOINT_MASS, DENSITY_OF_WATER * shape->getVolume()));
+            float mass = massScale * glm::max(MIN_JOINT_MASS, DENSITY_OF_WATER * shape->getVolume());
+            points[i].setMass(mass);
+            totalMass += mass;
         } else if (type == Shape::CAPSULE_SHAPE) {
             assert(parentIndex != -1);
             shape = new VerletCapsuleShape(radius, &(points[parentIndex]), &(points[i]));
             shape->setEntity(this);
-            points[i].setMass(massScale * glm::max(MIN_JOINT_MASS, DENSITY_OF_WATER * shape->getVolume()));
+            float mass = massScale * glm::max(MIN_JOINT_MASS, DENSITY_OF_WATER * shape->getVolume());
+            points[i].setMass(mass);
+            totalMass += mass;
         } 
         if (parentIndex != -1) {
             // always disable collisions between joint and its parent
             if (shape) {
                 disableCollisions(i, parentIndex);
             }
-        } else {
-            // give the base joint a very large mass since it doesn't actually move
-            // in the local-frame simulation (it defines the origin)
-            points[i].setMass(VERY_BIG_MASS);
-        }
+        } 
         _shapes.push_back(shape);
     }
 
+    // set the mass of the root
+    if (numStates > 0) {
+        points[0].setMass(totalMass);
+    }
+
     // This method moves the shapes to their default positions in Model frame.
     computeBoundingShape(geometry);
 
diff --git a/interface/src/avatar/SkeletonRagdoll.cpp b/interface/src/avatar/SkeletonRagdoll.cpp
index 503f38f00f..6318323990 100644
--- a/interface/src/avatar/SkeletonRagdoll.cpp
+++ b/interface/src/avatar/SkeletonRagdoll.cpp
@@ -70,10 +70,7 @@ void SkeletonRagdoll::buildConstraints() {
     for (int i = 0; i < numPoints; ++i) {
         const JointState& state = jointStates.at(i);
         int parentIndex = state.getParentIndex();
-        if (parentIndex == -1) {
-            FixedConstraint* anchor = new FixedConstraint(&_translationInSimulationFrame, &(_points[i]));
-            _fixedConstraints.push_back(anchor);
-        } else { 
+        if (parentIndex != -1) {
             DistanceConstraint* bone = new DistanceConstraint(&(_points[i]), &(_points[parentIndex]));
             bone->setDistance(state.getDistanceToParent());
             _boneConstraints.push_back(bone);
diff --git a/libraries/shared/src/PhysicsSimulation.cpp b/libraries/shared/src/PhysicsSimulation.cpp
index a62b3816af..6c4901bcd5 100644
--- a/libraries/shared/src/PhysicsSimulation.cpp
+++ b/libraries/shared/src/PhysicsSimulation.cpp
@@ -163,10 +163,10 @@ bool PhysicsSimulation::addRagdoll(Ragdoll* doll) {
 }
 
 void PhysicsSimulation::removeRagdoll(Ragdoll* doll) {
-    int numDolls = _otherRagdolls.size();
-    if (doll->_simulation != this) {
+    if (!doll || doll->_simulation != this) {
         return;
     }
+    int numDolls = _otherRagdolls.size();
     for (int i = 0; i < numDolls; ++i) {
         if (doll == _otherRagdolls[i]) {
             if (i == numDolls - 1) {
@@ -205,10 +205,11 @@ void PhysicsSimulation::stepForward(float deltaTime, float minError, int maxIter
         }
     }
 
+    bool collidedWithOtherRagdoll = false;
     int iterations = 0;
     float error = 0.0f;
     do {
-        computeCollisions();
+        collidedWithOtherRagdoll = computeCollisions() || collidedWithOtherRagdoll;
         updateContacts();
         resolveCollisions();
 
@@ -225,6 +226,14 @@ void PhysicsSimulation::stepForward(float deltaTime, float minError, int maxIter
         now = usecTimestampNow();
     } while (_collisions.size() != 0 && (iterations < maxIterations) && (error > minError) && (now < expiry));
 
+    // the collisions may have moved the main ragdoll from the simulation center
+    // so we remove this offset (potentially storing it as movement of the Ragdoll owner)
+    _ragdoll->removeRootOffset(collidedWithOtherRagdoll);
+
+    // also remove any offsets from the other ragdolls
+    for (int i = 0; i < numDolls; ++i) {
+        _otherRagdolls[i]->removeRootOffset(false);
+    }
     pruneContacts();
 }
 
@@ -237,7 +246,7 @@ void PhysicsSimulation::moveRagdolls(float deltaTime) {
     }
 }
 
-void PhysicsSimulation::computeCollisions() {
+bool PhysicsSimulation::computeCollisions() {
     PerformanceTimer perfTimer("collide");
     _collisions.clear();
 
@@ -258,11 +267,13 @@ void PhysicsSimulation::computeCollisions() {
     }
 
     // collide main ragdoll with others
+    bool otherCollisions = false;
     int numEntities = _otherEntities.size();
     for (int i = 0; i < numEntities; ++i) {
         const QVector<Shape*> otherShapes = _otherEntities.at(i)->getShapes();
-        ShapeCollider::collideShapesWithShapes(shapes, otherShapes, _collisions);
+        otherCollisions = ShapeCollider::collideShapesWithShapes(shapes, otherShapes, _collisions) || otherCollisions;
     }
+    return otherCollisions;
 }
 
 void PhysicsSimulation::resolveCollisions() {
diff --git a/libraries/shared/src/PhysicsSimulation.h b/libraries/shared/src/PhysicsSimulation.h
index 881007208b..1db56a46e2 100644
--- a/libraries/shared/src/PhysicsSimulation.h
+++ b/libraries/shared/src/PhysicsSimulation.h
@@ -53,9 +53,11 @@ public:
 
 protected:
     void moveRagdolls(float deltaTime);
-    void computeCollisions();
-    void resolveCollisions();
 
+    /// \return true if main ragdoll collides with other avatar
+    bool computeCollisions();
+
+    void resolveCollisions();
     void enforceContacts();
     void applyContactFriction();
     void updateContacts();