diff --git a/blocks/blockstore/blockstore.go b/blocks/blockstore/blockstore.go
index b4c0fd7fb..68ccc7c74 100644
--- a/blocks/blockstore/blockstore.go
+++ b/blocks/blockstore/blockstore.go
@@ -15,6 +15,8 @@ import (
 var ValueTypeMismatch = errors.New("The retrieved value is not a Block")
 
 type Blockstore interface {
+	DeleteBlock(u.Key) error
+	Has(u.Key) (bool, error)
 	Get(u.Key) (*blocks.Block, error)
 	Put(*blocks.Block) error
 }
@@ -45,3 +47,11 @@ func (bs *blockstore) Get(k u.Key) (*blocks.Block, error) {
 func (bs *blockstore) Put(block *blocks.Block) error {
 	return bs.datastore.Put(block.Key().DsKey(), block.Data)
 }
+
+func (bs *blockstore) Has(k u.Key) (bool, error) {
+	return bs.datastore.Has(k.DsKey())
+}
+
+func (s *blockstore) DeleteBlock(k u.Key) error {
+	return s.datastore.Delete(k.DsKey())
+}
diff --git a/blockservice/blocks_test.go b/blockservice/blocks_test.go
index 1e837eb5d..9f579c530 100644
--- a/blockservice/blocks_test.go
+++ b/blockservice/blocks_test.go
@@ -6,15 +6,18 @@ import (
 	"time"
 
 	"github.com/jbenet/go-ipfs/Godeps/_workspace/src/code.google.com/p/go.net/context"
-
 	ds "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-datastore"
+	dssync "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-datastore/sync"
 	blocks "github.com/jbenet/go-ipfs/blocks"
+	blockstore "github.com/jbenet/go-ipfs/blocks/blockstore"
+	offline "github.com/jbenet/go-ipfs/exchange/offline"
 	u "github.com/jbenet/go-ipfs/util"
 )
 
 func TestBlocks(t *testing.T) {
 	d := ds.NewMapDatastore()
-	bs, err := NewBlockService(d, nil)
+	tsds := dssync.MutexWrap(d)
+	bs, err := New(blockstore.NewBlockstore(tsds), offline.Exchange())
 	if err != nil {
 		t.Error("failed to construct block service", err)
 		return
diff --git a/blockservice/blockservice.go b/blockservice/blockservice.go
index 279e3ffd9..86e0c776b 100644
--- a/blockservice/blockservice.go
+++ b/blockservice/blockservice.go
@@ -9,9 +9,9 @@ import (
 
 	context "github.com/jbenet/go-ipfs/Godeps/_workspace/src/code.google.com/p/go.net/context"
 	ds "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-datastore"
-	mh "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-multihash"
 
 	blocks "github.com/jbenet/go-ipfs/blocks"
+	"github.com/jbenet/go-ipfs/blocks/blockstore"
 	exchange "github.com/jbenet/go-ipfs/exchange"
 	u "github.com/jbenet/go-ipfs/util"
 )
@@ -19,25 +19,28 @@ import (
 var log = u.Logger("blockservice")
 var ErrNotFound = errors.New("blockservice: key not found")
 
-// BlockService is a block datastore.
+// BlockService is a hybrid block datastore. It stores data in a local
+// datastore and may retrieve data from a remote Exchange.
 // It uses an internal `datastore.Datastore` instance to store values.
 type BlockService struct {
-	Datastore ds.Datastore
-	Remote    exchange.Interface
+	// TODO don't expose underlying impl details
+	Blockstore blockstore.Blockstore
+	Remote     exchange.Interface
 }
 
 // NewBlockService creates a BlockService with given datastore instance.
-func NewBlockService(d ds.Datastore, rem exchange.Interface) (*BlockService, error) {
-	if d == nil {
-		return nil, fmt.Errorf("BlockService requires valid datastore")
+func New(bs blockstore.Blockstore, rem exchange.Interface) (*BlockService, error) {
+	if bs == nil {
+		return nil, fmt.Errorf("BlockService requires valid blockstore")
 	}
 	if rem == nil {
 		log.Warning("blockservice running in local (offline) mode.")
 	}
-	return &BlockService{Datastore: d, Remote: rem}, nil
+	return &BlockService{Blockstore: bs, Remote: rem}, nil
 }
 
 // AddBlock adds a particular block to the service, Putting it into the datastore.
+// TODO pass a context into this if the remote.HasBlock is going to remain here.
 func (s *BlockService) AddBlock(b *blocks.Block) (u.Key, error) {
 	k := b.Key()
 	log.Debugf("blockservice: storing [%s] in datastore", k)
@@ -47,7 +50,7 @@ func (s *BlockService) AddBlock(b *blocks.Block) (u.Key, error) {
 	// check if we have it before adding. this is an extra read, but large writes
 	// are more expensive.
 	// TODO(jbenet) cheaper has. https://github.com/jbenet/go-datastore/issues/6
-	has, err := s.Datastore.Has(k.DsKey())
+	has, err := s.Blockstore.Has(k)
 	if err != nil {
 		return k, err
 	}
@@ -55,12 +58,14 @@ func (s *BlockService) AddBlock(b *blocks.Block) (u.Key, error) {
 		log.Debugf("blockservice: storing [%s] in datastore (already stored)", k)
 	} else {
 		log.Debugf("blockservice: storing [%s] in datastore", k)
-		err := s.Datastore.Put(k.DsKey(), b.Data)
+		err := s.Blockstore.Put(b)
 		if err != nil {
 			return k, err
 		}
 	}
 
+	// TODO this operation rate-limits blockservice operations, we should
+	// consider moving this to an sync process.
 	if s.Remote != nil {
 		ctx := context.TODO()
 		err = s.Remote.HasBlock(ctx, *b)
@@ -72,17 +77,11 @@ func (s *BlockService) AddBlock(b *blocks.Block) (u.Key, error) {
 // Getting it from the datastore using the key (hash).
 func (s *BlockService) GetBlock(ctx context.Context, k u.Key) (*blocks.Block, error) {
 	log.Debugf("BlockService GetBlock: '%s'", k)
-	datai, err := s.Datastore.Get(k.DsKey())
+	block, err := s.Blockstore.Get(k)
 	if err == nil {
-		log.Debug("Blockservice: Got data in datastore.")
-		bdata, ok := datai.([]byte)
-		if !ok {
-			return nil, fmt.Errorf("data associated with %s is not a []byte", k)
-		}
-		return &blocks.Block{
-			Multihash: mh.Multihash(k),
-			Data:      bdata,
-		}, nil
+		return block, nil
+		// TODO be careful checking ErrNotFound. If the underlying
+		// implementation changes, this will break.
 	} else if err == ds.ErrNotFound && s.Remote != nil {
 		log.Debug("Blockservice: Searching bitswap.")
 		blk, err := s.Remote.GetBlock(ctx, k)
@@ -101,21 +100,13 @@ func (s *BlockService) GetBlocks(ctx context.Context, ks []u.Key) <-chan *blocks
 	go func() {
 		var toFetch []u.Key
 		for _, k := range ks {
-			datai, err := s.Datastore.Get(k.DsKey())
-			if err == nil {
-				log.Debug("Blockservice: Got data in datastore.")
-				bdata, ok := datai.([]byte)
-				if !ok {
-					log.Criticalf("data associated with %s is not a []byte", k)
-					continue
-				}
-				out <- &blocks.Block{
-					Multihash: mh.Multihash(k),
-					Data:      bdata,
-				}
-			} else {
+			block, err := s.Blockstore.Get(k)
+			if err != nil {
 				toFetch = append(toFetch, k)
+				continue
 			}
+			log.Debug("Blockservice: Got data in datastore.")
+			out <- block
 		}
 	}()
 	return out
@@ -123,5 +114,5 @@ func (s *BlockService) GetBlocks(ctx context.Context, ks []u.Key) <-chan *blocks
 
 // DeleteBlock deletes a block in the blockservice from the datastore
 func (s *BlockService) DeleteBlock(k u.Key) error {
-	return s.Datastore.Delete(k.DsKey())
+	return s.Blockstore.DeleteBlock(k)
 }
diff --git a/core/core.go b/core/core.go
index a0d07d9af..fcd421fc6 100644
--- a/core/core.go
+++ b/core/core.go
@@ -15,6 +15,7 @@ import (
 	exchange "github.com/jbenet/go-ipfs/exchange"
 	bitswap "github.com/jbenet/go-ipfs/exchange/bitswap"
 	bsnet "github.com/jbenet/go-ipfs/exchange/bitswap/network"
+	"github.com/jbenet/go-ipfs/exchange/offline"
 	mount "github.com/jbenet/go-ipfs/fuse/mount"
 	merkledag "github.com/jbenet/go-ipfs/merkledag"
 	namesys "github.com/jbenet/go-ipfs/namesys"
@@ -127,6 +128,8 @@ func NewIpfsNode(cfg *config.Config, online bool) (n *IpfsNode, err error) {
 		return nil, debugerror.Wrap(err)
 	}
 
+	n.Exchange = offline.Exchange()
+
 	// setup online services
 	if online {
 
@@ -178,7 +181,7 @@ func NewIpfsNode(cfg *config.Config, online bool) (n *IpfsNode, err error) {
 
 	// TODO(brian): when offline instantiate the BlockService with a bitswap
 	// session that simply doesn't return blocks
-	n.Blocks, err = bserv.NewBlockService(n.Datastore, n.Exchange)
+	n.Blocks, err = bserv.New(blockstore.NewBlockstore(n.Datastore), n.Exchange)
 	if err != nil {
 		return nil, debugerror.Wrap(err)
 	}
diff --git a/core/mock.go b/core/mock.go
index 92ffcb57d..2d2359277 100644
--- a/core/mock.go
+++ b/core/mock.go
@@ -3,8 +3,10 @@ package core
 import (
 	ds "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-datastore"
 	syncds "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-datastore/sync"
-	bs "github.com/jbenet/go-ipfs/blockservice"
+	"github.com/jbenet/go-ipfs/blocks/blockstore"
+	blockservice "github.com/jbenet/go-ipfs/blockservice"
 	ci "github.com/jbenet/go-ipfs/crypto"
+	"github.com/jbenet/go-ipfs/exchange/offline"
 	mdag "github.com/jbenet/go-ipfs/merkledag"
 	nsys "github.com/jbenet/go-ipfs/namesys"
 	path "github.com/jbenet/go-ipfs/path"
@@ -43,9 +45,7 @@ func NewMockNode() (*IpfsNode, error) {
 	nd.Routing = dht
 
 	// Bitswap
-	//??
-
-	bserv, err := bs.NewBlockService(nd.Datastore, nil)
+	bserv, err := blockservice.New(blockstore.NewBlockstore(nd.Datastore), offline.Exchange())
 	if err != nil {
 		return nil, err
 	}
diff --git a/pin/pin_test.go b/pin/pin_test.go
index 1ea302823..fc9dc215d 100644
--- a/pin/pin_test.go
+++ b/pin/pin_test.go
@@ -4,7 +4,10 @@ import (
 	"testing"
 
 	ds "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-datastore"
+	dssync "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-datastore/sync"
+	"github.com/jbenet/go-ipfs/blocks/blockstore"
 	bs "github.com/jbenet/go-ipfs/blockservice"
+	"github.com/jbenet/go-ipfs/exchange/offline"
 	mdag "github.com/jbenet/go-ipfs/merkledag"
 	"github.com/jbenet/go-ipfs/util"
 )
@@ -19,13 +22,15 @@ func randNode() (*mdag.Node, util.Key) {
 
 func TestPinnerBasic(t *testing.T) {
 	dstore := ds.NewMapDatastore()
-	bserv, err := bs.NewBlockService(dstore, nil)
+	bstore := blockstore.NewBlockstore(dssync.MutexWrap(dstore))
+	bserv, err := bs.New(bstore, offline.Exchange())
 	if err != nil {
 		t.Fatal(err)
 	}
 
 	dserv := mdag.NewDAGService(bserv)
 
+	// TODO does pinner need to share datastore with blockservice?
 	p := NewPinner(dstore, dserv)
 
 	a, ak := randNode()
diff --git a/unixfs/io/dagmodifier_test.go b/unixfs/io/dagmodifier_test.go
index 822c87471..d0aa83795 100644
--- a/unixfs/io/dagmodifier_test.go
+++ b/unixfs/io/dagmodifier_test.go
@@ -6,7 +6,10 @@ import (
 	"io/ioutil"
 	"testing"
 
+	"github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-datastore/sync"
+	"github.com/jbenet/go-ipfs/blocks/blockstore"
 	bs "github.com/jbenet/go-ipfs/blockservice"
+	"github.com/jbenet/go-ipfs/exchange/offline"
 	imp "github.com/jbenet/go-ipfs/importer"
 	"github.com/jbenet/go-ipfs/importer/chunk"
 	mdag "github.com/jbenet/go-ipfs/merkledag"
@@ -19,7 +22,9 @@ import (
 
 func getMockDagServ(t *testing.T) mdag.DAGService {
 	dstore := ds.NewMapDatastore()
-	bserv, err := bs.NewBlockService(dstore, nil)
+	tsds := sync.MutexWrap(dstore)
+	bstore := blockstore.NewBlockstore(tsds)
+	bserv, err := bs.New(bstore, offline.Exchange())
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/util/testutil/gen.go b/util/testutil/gen.go
index be2fe5988..c7f310c2a 100644
--- a/util/testutil/gen.go
+++ b/util/testutil/gen.go
@@ -4,9 +4,12 @@ import (
 	crand "crypto/rand"
 	"testing"
 
+	dssync "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-datastore/sync"
+	"github.com/jbenet/go-ipfs/exchange/offline"
 	"github.com/jbenet/go-ipfs/peer"
 
 	ds "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-datastore"
+	"github.com/jbenet/go-ipfs/blocks/blockstore"
 	bsrv "github.com/jbenet/go-ipfs/blockservice"
 	dag "github.com/jbenet/go-ipfs/merkledag"
 	u "github.com/jbenet/go-ipfs/util"
@@ -14,7 +17,8 @@ import (
 
 func GetDAGServ(t testing.TB) dag.DAGService {
 	dstore := ds.NewMapDatastore()
-	bserv, err := bsrv.NewBlockService(dstore, nil)
+	tsds := dssync.MutexWrap(dstore)
+	bserv, err := bsrv.New(blockstore.NewBlockstore(tsds), offline.Exchange())
 	if err != nil {
 		t.Fatal(err)
 	}