diff --git a/ruby/lib/jam_ruby/models/active_music_session.rb b/ruby/lib/jam_ruby/models/active_music_session.rb
index 937f3ad20..cc97f572c 100644
--- a/ruby/lib/jam_ruby/models/active_music_session.rb
+++ b/ruby/lib/jam_ruby/models/active_music_session.rb
@@ -320,7 +320,7 @@ module JamRuby
 
       connection = Connection.where(user_id: current_user.id, client_id: client_id).first!
       my_locidispid = connection.locidispid
-      my_audio_latency = connection.last_jam_audio_latency
+      my_audio_latency = connection.last_jam_audio_latency || 0 # we can't assume that the user has an audio_latency when searching
 
       self.connection.execute("select ams_index('#{current_user.id}'::varchar, #{my_locidispid}::bigint, #{my_audio_latency}::integer)");
     end
@@ -407,6 +407,7 @@ module JamRuby
 
     # returns the set of users in a music_sessions and the music_session they are in and their latency.
     # ams_init must be called first.
+    # user.audio_latency / 2 , + other_user.audio_latency of them / 2, + network latency /2
     def self.ams_users()
       return User.select('users.*, ams_users_tmp.music_session_id, ams_users_tmp.latency')
       .joins(
diff --git a/ruby/lib/jam_ruby/models/connection.rb b/ruby/lib/jam_ruby/models/connection.rb
index fc3d43682..ac40e38ca 100644
--- a/ruby/lib/jam_ruby/models/connection.rb
+++ b/ruby/lib/jam_ruby/models/connection.rb
@@ -169,10 +169,6 @@ module JamRuby
     end
 
     def associate_tracks(tracks)
-      # @log.debug "Tracks:"
-      # @log.debug tracks
-
-
       unless tracks.nil?
         self.tracks.clear()
         tracks.each do |track|
diff --git a/web/app/controllers/api_music_sessions_controller.rb b/web/app/controllers/api_music_sessions_controller.rb
index 7f4f7f09e..f633c3c7b 100644
--- a/web/app/controllers/api_music_sessions_controller.rb
+++ b/web/app/controllers/api_music_sessions_controller.rb
@@ -83,7 +83,14 @@ class ApiMusicSessionsController < ApiController
                                                   offset: params[:offset],
                                                   limit: params[:limit]).all
 
-      @music_session_users = ActiveMusicSession.ams_users().all
+      music_session_users = ActiveMusicSession.ams_users.all
+
+      @user_scores = {}
+      music_session_users.each do |user|
+        @user_scores[user.id] = {latency: user.latency}
+      end
+
+      render "api_music_sessions/ams_index"
     end
   end
 
diff --git a/web/app/helpers/score_helper.rb b/web/app/helpers/score_helper.rb
new file mode 100644
index 000000000..1609e2378
--- /dev/null
+++ b/web/app/helpers/score_helper.rb
@@ -0,0 +1,9 @@
+module ScoreHelper
+
+  # helper method to make finding a user's score fault-tolerant
+  def user_score(user_id)
+    @user_scores ||= {}
+    user = @user_scores[user_id]
+    user ? user[:latency] : nil
+  end
+end
diff --git a/web/app/views/api_music_sessions/ams_index.rabl b/web/app/views/api_music_sessions/ams_index.rabl
new file mode 100644
index 000000000..05e15a27f
--- /dev/null
+++ b/web/app/views/api_music_sessions/ams_index.rabl
@@ -0,0 +1,3 @@
+object @music_sessions
+
+extends "api_music_sessions/show_history"
diff --git a/web/app/views/api_music_sessions/show_history.rabl b/web/app/views/api_music_sessions/show_history.rabl
index 444e06a3c..162fbdb32 100644
--- a/web/app/views/api_music_sessions/show_history.rabl
+++ b/web/app/views/api_music_sessions/show_history.rabl
@@ -74,6 +74,15 @@ else
     attributes :id, :sender_id, :receiver_id
   }
 
+  child({:approved_rsvps => :approved_rsvps}) {
+      attributes :id, :photo_url, :first_name, :last_name, :instrument_id
+
+      node do |user|
+        { latency: user_score(user.id) }
+      end
+
+  }
+
 
   child(:active_music_session => :active_music_session) {
     attributes :claimed_recording_initiator_id, :track_changes_counter
@@ -99,7 +108,7 @@ else
       attributes :ip_address, :client_id, :joined_session_at
 
       node :user do |connection|
-        { :id => connection.user.id, :photo_url => connection.user.photo_url, :name => connection.user.name, :is_friend => connection.user.friends?(current_user), :connection_state => connection.aasm_state }
+        { :id => connection.user.id, :photo_url => connection.user.photo_url, :name => connection.user.name, :is_friend => connection.user.friends?(current_user), :connection_state => connection.aasm_state, latency: user_score(connection.user.id)   }
       end
 
       child(:tracks => :tracks) {
@@ -107,8 +116,6 @@ else
       }
     }
 
-
-
     # only show join_requests if the current_user is in the session
     node(:join_requests, :if => lambda { |music_session| music_session.users.exists?(current_user) } ) do |music_session|
       child(:join_requests => :join_requests) {
diff --git a/web/config/routes.rb b/web/config/routes.rb
index e3012cfcd..9107f09d2 100644
--- a/web/config/routes.rb
+++ b/web/config/routes.rb
@@ -153,6 +153,7 @@ SampleApp::Application.routes.draw do
     match '/participants/:id' => 'api_music_sessions#participant_delete', :via => :delete
     match '/sessions/scheduled' => 'api_music_sessions#scheduled', :via => :get
     match '/sessions/legacy' => 'api_music_sessions#create_legacy', :via => :post
+    match '/sessions/active' => 'api_music_sessions#ams_index', :via => :get
     match '/sessions/:id' => 'api_music_sessions#show', :via => :get, :as => 'api_session_detail'
     match '/sessions/:id' => 'api_music_sessions#update', :via => :put
     match '/sessions/:id' => 'api_music_sessions#session_update', :via => :post
@@ -166,7 +167,7 @@ SampleApp::Application.routes.draw do
     match '/sessions/:id/history' => 'api_music_sessions#show_history', :via => :get, :as => 'api_session_history_detail'
 
     match '/sessions/:id/details/comments' => 'api_music_sessions#add_session_info_comment', :via => :post
-    
+
     # music session tracks
     match '/sessions/:id/tracks' => 'api_music_sessions#track_create', :via => :post
     match '/sessions/:id/tracks' => 'api_music_sessions#track_sync', :via => :put
diff --git a/web/spec/controllers/api_music_sessions_controller_spec.rb b/web/spec/controllers/api_music_sessions_controller_spec.rb
new file mode 100644
index 000000000..31a948bd8
--- /dev/null
+++ b/web/spec/controllers/api_music_sessions_controller_spec.rb
@@ -0,0 +1,87 @@
+require 'spec_helper'
+
+describe ApiMusicSessionsController do
+  render_views
+
+  let(:tracks) { [{'sound' => 'mono', 'client_track_id' => 'abc', 'instrument_id' => 'piano'}] }
+  let(:user) { FactoryGirl.create(:user) }
+  let (:conn) { FactoryGirl.create(:connection, :user => user) }
+
+  let(:other) { FactoryGirl.create(:user) }
+  let (:other_conn) { FactoryGirl.create(:connection, user: other, ip_address: '2.2.2.2') }
+
+  let(:third_user) { FactoryGirl.create(:user) }
+
+  before(:each) do
+    controller.current_user = user
+
+    ActiveMusicSession.delete_all
+    MusicSession.delete_all
+  end
+
+  describe "ams_index" do
+
+    it "no results" do
+      get :ams_index, {client_id: conn.client_id}
+      response.should be_success
+      json = JSON.parse(response.body, :symbolize_names => true)
+      json.length.should == 0
+    end
+
+    it "just self" do
+      # create a session with self in it
+      ams = FactoryGirl.create(:active_music_session, creator: user)
+      conn.join_the_session(ams.music_session, true, tracks, user, 10)
+      conn.errors.any?.should be_false
+
+      get :ams_index, {client_id: conn.client_id}
+      json = JSON.parse(response.body, :symbolize_names => true)
+      json.length.should == 1
+      json[0][:active_music_session][:participants][0][:user][:latency].should be_nil
+    end
+
+    it "someone else with no score with self" do
+      # create a session with someone else in it, but no score
+      ams = FactoryGirl.create(:active_music_session, creator: other)
+      other_conn.join_the_session(ams.music_session, true, tracks, user, 10)
+      other_conn.errors.any?.should be_false
+
+      get :ams_index, {client_id: conn.client_id}
+      json = JSON.parse(response.body, :symbolize_names => true)
+      json.length.should == 1
+      json[0][:active_music_session][:participants][0][:user][:latency].should be_nil
+    end
+
+    it "someone else with a score with a self" do
+      # create a session with someone else in it, but no score
+      ams = FactoryGirl.create(:active_music_session, creator: other)
+      other_conn.join_the_session(ams.music_session, true, tracks, other, 10)
+      other_conn.errors.any?.should be_false
+      Score.createx(conn.locidispid, conn.client_id, conn.addr, other_conn.locidispid, other_conn.client_id, other_conn.addr, 20, nil)
+
+      get :ams_index, {client_id: conn.client_id}
+      json = JSON.parse(response.body, :symbolize_names => true)
+      json.length.should == 1
+      json[0][:active_music_session][:participants][0][:user][:latency].should == 17.5
+    end
+
+    it "someone else with a score with a self, and another with an approved RSVP" do
+      # create a session with someone else in it, but no score
+      ams = FactoryGirl.create(:active_music_session, creator: other)
+      other_conn.join_the_session(ams.music_session, true, tracks, other, 10)
+      other_conn.errors.any?.should be_false
+      Score.createx(conn.locidispid, conn.client_id, conn.addr, other_conn.locidispid, other_conn.client_id, other_conn.addr, 20, nil)
+
+      rsvp_slot = FactoryGirl.create(:rsvp_slot, music_session: ams.music_session, instrument: Instrument.find('piano'))
+      rsvp_request = FactoryGirl.create(:rsvp_request, user: third_user)
+      rsvp_request_rsvp_slot = FactoryGirl.create(:rsvp_request_rsvp_slot, chosen:true, rsvp_request: rsvp_request, rsvp_slot:rsvp_slot)
+
+      get :ams_index, {client_id: conn.client_id}
+      json = JSON.parse(response.body, :symbolize_names => true)
+      json.length.should == 1
+      json[0][:active_music_session][:participants][0][:user][:latency].should_not be_nil
+      json[0][:approved_rsvps][0][:id].should == third_user.id
+      json[0][:approved_rsvps][0][:latency].should == 17.5
+    end
+  end
+end
diff --git a/web/spec/factories.rb b/web/spec/factories.rb
index 1691838c8..0c8cd23f8 100644
--- a/web/spec/factories.rb
+++ b/web/spec/factories.rb
@@ -15,6 +15,7 @@ FactoryGirl.define do
     country "US"
     terms_of_service true
     subscribe_email true
+    last_jam_audio_latency 5
 
     factory :fan do
       musician false
@@ -132,7 +133,7 @@ FactoryGirl.define do
     sequence(:client_id) { |n| "client_id#{n}"}
     ip_address "1.1.1.1"
     as_musician true
-    addr 0
+    addr {JamIsp.ip_to_num(ip_address)}
     locidispid 0
     client_type 'client'
   end
@@ -483,6 +484,10 @@ FactoryGirl.define do
     cancel_all false
   end
 
+  factory :rsvp_request_rsvp_slot, class: JamRuby::RsvpRequestRsvpSlot do
+    chosen false
+  end
+
   factory :diagnostic, :class => JamRuby::Diagnostic do
     type JamRuby::Diagnostic::NO_HEARTBEAT_ACK
     creator JamRuby::Diagnostic::CLIENT