diff --git a/lib/mongo/node.rb b/lib/mongo/node.rb
index aa9a302..b13f5b5 100644
--- a/lib/mongo/node.rb
+++ b/lib/mongo/node.rb
@@ -86,7 +86,7 @@ module Mongo
 
         check_set_membership(config)
         check_set_name(config)
-      rescue ReplicaSetConnectionError, OperationFailure, SocketError, SystemCallError, IOError => ex
+      rescue ConnectionFailure, OperationFailure, SocketError, SystemCallError, IOError => ex
         self.connection.log(:warn, "Attempted connection to node #{host_string} raised " +
                             "#{ex.class}: #{ex.message}")
         return nil
@@ -158,7 +158,7 @@ module Mongo
       if !config['hosts']
         message = "Will not connect to #{host_string} because it's not a member " +
           "of a replica set."
-        raise ReplicaSetConnectionError, message
+        raise ConnectionFailure, message
       end
     end
 
diff --git a/lib/mongo/repl_set_connection.rb b/lib/mongo/repl_set_connection.rb
index 32cc25c..d60b882 100644
--- a/lib/mongo/repl_set_connection.rb
+++ b/lib/mongo/repl_set_connection.rb
@@ -16,12 +16,14 @@
 # limitations under the License.
 # ++
 
+require 'sync'
+
 module Mongo
 
   # Instantiates and manages connections to a MongoDB replica set.
   class ReplSetConnection < Connection
     attr_reader :nodes, :secondaries, :arbiters, :secondary_pools,
-      :replica_set_name, :read_pool, :seeds, :tags_to_pools
+      :replica_set_name, :read_pool, :seeds, :tags_to_pools, :refresh_interval
 
     # Create a connection to a MongoDB replica set.
     #
@@ -74,6 +76,8 @@ module Mongo
     # @raise [ReplicaSetConnectionError] This is raised if a replica set name is specified and the
     #   driver fails to connect to a replica set with that name.
     def initialize(*args)
+      extend Sync_m
+
       if args.last.is_a?(Hash)
         opts = args.pop
       else
@@ -87,6 +91,7 @@ module Mongo
       # The list of seed nodes
       @seeds = args
 
+      # TODO: get rid of this
       @nodes = @seeds.dup
 
       # The members of the replica set, stored as instances of Mongo::Node.
@@ -121,8 +126,6 @@ module Mongo
         @read = opts.fetch(:read, :primary)
       end
 
-      # Lock around changes to the global config
-      @connection_lock = Mutex.new
       @connected = false
 
       # Store the refresher thread
@@ -146,7 +149,7 @@ module Mongo
 
     # Initiate a connection to the replica set.
     def connect
-      @connection_lock.synchronize do
+      sync_synchronize(:EX) do
         return if @connected
         manager = PoolManager.new(self, @seeds)
         manager.connect
@@ -163,11 +166,12 @@ module Mongo
     end
 
     # Note: this method must be called from within
-    # a locked @connection_lock
+    # an exclusive lock.
     def update_config(manager)
       @arbiters = manager.arbiters.nil? ? [] : manager.arbiters.dup
       @primary = manager.primary.nil? ? nil : manager.primary.dup
       @secondaries = manager.secondaries.dup
+      @hosts = manager.hosts.dup
 
       @primary_pool = manager.primary_pool
       @read_pool    = manager.read_pool
@@ -175,7 +179,6 @@ module Mongo
       @tags_to_pools   = manager.tags_to_pools
       @seeds = manager.seeds
       @manager = manager
-      @hosts = manager.hosts
       @nodes = manager.nodes
       @max_bson_size = manager.max_bson_size
     end
@@ -193,16 +196,18 @@ module Mongo
       end
 
       background_manager = Thread.current[:background]
-      if update_struct = background_manager.update_required?(@hosts)
-        @connection_lock.synchronize do
-          background_manager.update(@manager, update_struct)
+      if background_manager.update_required?(@hosts)
+        sync_synchronize(:EX) do
+          background_manager.connect
           update_config(background_manager)
         end
       end
     end
 
     def connected?
-      @connected && !@connection_lock.locked?
+      sync_synchronize(:SH) do
+        @connected
+      end
     end
 
     # @deprecated
@@ -234,7 +239,9 @@ module Mongo
     #
     # @return [Boolean]
     def read_primary?
-      @read_pool == @primary_pool
+      sync_synchronize(:SH) do
+        @read_pool == @primary_pool
+      end
     end
     alias :primary? :read_primary?
 
@@ -243,10 +250,12 @@ module Mongo
     end
 
     # Close the connection to the database.
+    # TODO: we should get an exclusive lock here.
     def close
+      @connected = false
+
       super
 
-      @connected = false
       if @refresh_thread
         @refresh_thread.kill
         @refresh_thread = nil
@@ -314,8 +323,10 @@ module Mongo
       return unless @auto_refresh
       return if @refresh_thread && @refresh_thread.alive?
       @refresh_thread = Thread.new do
-        sleep(@refresh_interval)
-        refresh
+        while true do
+          sleep(@refresh_interval)
+          refresh
+        end
       end
     end
 
@@ -325,21 +336,25 @@ module Mongo
     def checkout_reader
       connect unless connected?
 
-      socket = @read_pool.checkout
-      @sockets_to_pools[socket] = @read_pool
-      return socket
+      sync_synchronize(:SH) do
+        socket = @read_pool.checkout
+        @sockets_to_pools[socket] = @read_pool
+        socket
+      end
     end
 
     # Checkout a socket connected to a node with one of
     # the provided tags. If no such node exists, raise
     # an exception.
     def checkout_tagged(tags)
-      tags.each do |k, v|
-        pools = @tags_to_pools[{k => v}]
-        if !pools.empty?
-          socket = pools.first.checkout
-          @sockets_to_pools[socket] = pools.first
-          return socket
+      sync_synchronize(:SH) do
+        tags.each do |k, v|
+          pools = @tags_to_pools[{k => v}]
+          if !pools.empty?
+            socket = pools.first.checkout
+            @sockets_to_pools[socket] = pools.first
+            socket
+          end
         end
       end
 
@@ -351,16 +366,13 @@ module Mongo
     def checkout_writer
       connect unless connected?
 
-      if @primary_pool
-        begin
+      sync_synchronize(:SH) do
+        if @primary_pool
           socket = @primary_pool.checkout
           @sockets_to_pools[socket] = @primary_pool
-          return socket
-        rescue NoMethodError
+          socket
         end
       end
-
-      raise ConnectionFailure, "Failed to connect to primary node."
     end
 
     # Checkin a socket used for reading.
diff --git a/lib/mongo/util/pool_manager.rb b/lib/mongo/util/pool_manager.rb
index df5ae73..e12f3b2 100644
--- a/lib/mongo/util/pool_manager.rb
+++ b/lib/mongo/util/pool_manager.rb
@@ -29,7 +29,7 @@ module Mongo
     # If we're connected to nodes that are no longer part of the set,
     # remove these from our set of secondary pools.
     def update_required?(hosts)
-      if !@refresh_node || !@refresh_node.active?
+      if !@refresh_node || !@refresh_node.set_config
         begin
           @refresh_node = get_valid_seed_node
         rescue ConnectionFailure
@@ -37,22 +37,13 @@ module Mongo
           return
         end
       end
-      node = @refresh_node
 
-      node_list = node.node_list
-
-      unconnected_nodes = node_list - hosts
-      removed_nodes = hosts - node_list
-
-      if unconnected_nodes.empty? && removed_nodes.empty?
-        return false
-      else
-        {:unconnected => unconnected_nodes, :removed => removed_nodes}
-      end
+      hosts != @refresh_node.node_list
     end
 
     def update(manager, node_struct)
       reference_manager_data(manager)
+
       unconnected_nodes = node_struct[:unconnected]
       removed_nodes = node_struct[:removed]
 
@@ -104,8 +95,8 @@ module Mongo
       @arbiters = []
       @secondaries = []
       @secondary_pools = []
-      @hosts = []
-      @members = []
+      @hosts = Set.new
+      @members = Set.new
       @tags_to_pools = {}
     end
 
diff --git a/test/replica_sets/connect_test.rb b/test/replica_sets/connect_test.rb
index 3ce994e..95bd8b6 100644
--- a/test/replica_sets/connect_test.rb
+++ b/test/replica_sets/connect_test.rb
@@ -20,7 +20,7 @@ class ConnectTest < Test::Unit::TestCase
   def test_connect_bad_name
     assert_raise_error(ReplicaSetConnectionError, "-wrong") do
       @conn = ReplSetConnection.new([RS.host, RS.ports[0]], [RS.host, RS.ports[1]],
-        [RS.host, RS.ports[2]], :rs_name => RS.name + "-wrong")
+        [RS.host, RS.ports[2]], :name => RS.name + "-wrong")
     end
   end
 
diff --git a/test/replica_sets/reconfigure_test.rb b/test/replica_sets/reconfigure_test.rb
deleted file mode 100644
index 5b0a2ac..0000000
--- a/test/replica_sets/reconfigure_test.rb
+++ /dev/null
@@ -1,34 +0,0 @@
-$:.unshift(File.join(File.dirname(__FILE__), '..', 'lib'))
-require './test/replica_sets/rs_test_helper'
-
-class ReplicaSetReconfigureTest < Test::Unit::TestCase
-  include Mongo
-
-  def setup
-    @conn = ReplSetConnection.new([RS.host, RS.ports[0]])
-    @db = @conn.db(MONGO_TEST_DB)
-    @db.drop_collection("test-sets")
-    @coll = @db.collection("test-sets")
-  end
-
-  def teardown
-    RS.restart_killed_nodes
-    @conn.close if @conn
-  end
-
-  def test_query
-    assert @coll.save({:a => 1}, :safe => {:w => 3})
-    RS.add_node
-    assert_raise_error(Mongo::ConnectionFailure, "") do
-      @coll.save({:a => 1}, :safe => {:w => 3})
-    end
-    assert @coll.save({:a => 1}, :safe => {:w => 3})
-  end
-
-  def benchmark_queries
-    t1 = Time.now
-    10000.times { @coll.find_one }
-    Time.now - t1
-  end
-
-end
diff --git a/test/replica_sets/refresh_test.rb b/test/replica_sets/refresh_test.rb
index fcf65c0..f35d04d 100644
--- a/test/replica_sets/refresh_test.rb
+++ b/test/replica_sets/refresh_test.rb
@@ -2,7 +2,6 @@ $:.unshift(File.join(File.dirname(__FILE__), '..', 'lib'))
 require './test/replica_sets/rs_test_helper'
 require 'benchmark'
 
-# NOTE: This test expects a replica set of three nodes to be running on RS.host,
 # on ports TEST_PORT, RS.ports[1], and TEST + 2.
 class ReplicaSetRefreshTest < Test::Unit::TestCase
   include Mongo
@@ -12,6 +11,27 @@ class ReplicaSetRefreshTest < Test::Unit::TestCase
     @conn.close if @conn
   end
 
+  def test_connect_speed
+    Benchmark.bm do |x|
+      x.report("Connect") do
+        10.times do
+          ReplSetConnection.new([RS.host, RS.ports[0]], [RS.host, RS.ports[1]],
+            [RS.host, RS.ports[2]], :auto_refresh => false)
+        end
+      end
+
+          @con = ReplSetConnection.new([RS.host, RS.ports[0]], [RS.host, RS.ports[1]],
+            [RS.host, RS.ports[2]], :auto_refresh => false)
+
+      x.report("manager") do
+        man = Mongo::PoolManager.new(@con, @con.seeds)
+        10.times do
+          man.connect
+        end
+      end
+    end
+  end
+
   def test_connect_and_manual_refresh_with_secondaries_down
     RS.kill_all_secondaries
 
@@ -65,14 +85,36 @@ class ReplicaSetRefreshTest < Test::Unit::TestCase
     @conn = ReplSetConnection.new([RS.host, RS.ports[0]], [RS.host, RS.ports[1]],
       [RS.host, RS.ports[2]], :refresh_interval => 2, :auto_refresh => true)
 
-    assert_equal 2, @conn.secondaries.length
     assert_equal 2, @conn.secondary_pools.length
+    assert_equal 2, @conn.secondaries.length
 
-    RS.remove_secondary_node
+    n = RS.remove_secondary_node
     sleep(4)
 
     assert_equal 1, @conn.secondaries.length
     assert_equal 1, @conn.secondary_pools.length
+
+    RS.add_node(n)
   end
 
+  def test_adding_and_removing_nodes
+    puts "ADDING AND REMOVING"
+    @conn = ReplSetConnection.new([RS.host, RS.ports[0]], [RS.host, RS.ports[1]],
+      [RS.host, RS.ports[2]], :refresh_interval => 2, :auto_refresh => true)
+
+    RS.add_node
+    sleep(5)
+
+    @conn2 = ReplSetConnection.new([RS.host, RS.ports[0]], [RS.host, RS.ports[1]],
+      [RS.host, RS.ports[2]], :refresh_interval => 2, :auto_refresh => true)
+
+    assert @conn2.secondaries == @conn.secondaries
+    assert_equal 3, @conn.secondary_pools.length
+    assert_equal 3, @conn.secondaries.length
+
+    RS.remove_secondary_node
+    sleep(4)
+    assert_equal 2, @conn.secondary_pools.length
+    assert_equal 2, @conn.secondaries.length
+  end
 end
diff --git a/test/tools/repl_set_manager.rb b/test/tools/repl_set_manager.rb
index 48128ab..034ba30 100644
--- a/test/tools/repl_set_manager.rb
+++ b/test/tools/repl_set_manager.rb
@@ -132,25 +132,25 @@ class ReplSetManager
     config = con['local']['system.replset'].find_one
     secondary = get_node_with_state(2)
     host_port = "#{@host}:#{@mongods[secondary]['port']}"
+    kill(secondary)
+    @mongods.delete(secondary)
     @config['members'].reject! {|m| m['host'] == host_port}
-
     @config['version'] = config['version'] + 1
 
-    primary = get_node_with_state(1)
-    con = get_connection(primary)
-
     begin
     con['admin'].command({'replSetReconfig' => @config})
     rescue Mongo::ConnectionFailure
     end
 
     con.close
+
+    return secondary
   end
 
-  def add_node
+  def add_node(n=nil)
     primary = get_node_with_state(1)
     con = get_connection(primary)
-    init_node(@mongods.length)
+    init_node(n || @mongods.length)
 
     config = con['local']['system.replset'].find_one
     @config['version'] = config['version'] + 1