diff --git a/libp2p/peerstore.nim b/libp2p/peerstore.nim
new file mode 100644
index 0000000..85787e8
--- /dev/null
+++ b/libp2p/peerstore.nim
@@ -0,0 +1,170 @@
+## Nim-LibP2P
+## Copyright (c) 2021 Status Research & Development GmbH
+## Licensed under either of
+##  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
+##  * MIT license ([LICENSE-MIT](LICENSE-MIT))
+## at your option.
+## This file may not be copied, modified, or distributed except according to
+## those terms.
+
+{.push raises: [Defect].}
+
+import
+  std/[tables, sets, sequtils],
+  ./crypto/crypto,
+  ./peerid,
+  ./multiaddress
+
+type
+  #################
+  # Handler types #
+  #################
+
+  PeerBookChangeHandler*[T] = proc(peerId: PeerID, entry: T)
+
+  AddrChangeHandler* = PeerBookChangeHandler[HashSet[MultiAddress]]
+  ProtoChangeHandler* = PeerBookChangeHandler[HashSet[string]]
+  KeyChangeHandler* = PeerBookChangeHandler[PublicKey]
+  
+  #########
+  # Books #
+  #########
+
+  # Each book contains a book (map) and event handler(s)
+  PeerBook*[T] = object of RootObj
+    book*: Table[PeerID, T]
+    changeHandlers: seq[PeerBookChangeHandler[T]]
+  
+  AddressBook* = object of PeerBook[HashSet[MultiAddress]]
+  ProtoBook* = object of PeerBook[HashSet[string]]
+  KeyBook* = object of PeerBook[PublicKey]
+  
+  ####################
+  # Peer store types #
+  ####################
+
+  PeerStore* = ref object of RootObj
+    addressBook*: AddressBook
+    protoBook*: ProtoBook
+    keyBook*: KeyBook
+  
+  StoredInfo* = object
+    # Collates stored info about a peer
+    peerId*: PeerID    
+    addrs*: HashSet[MultiAddress]
+    protos*: HashSet[string]
+    publicKey*: PublicKey
+
+## Constructs a new PeerStore with metadata of type M
+proc new*(T: type PeerStore): PeerStore =
+  var p: PeerStore
+  new(p)
+  return p
+
+#########################
+# Generic Peer Book API #
+#########################
+
+proc get*[T](peerBook: PeerBook[T],
+             peerId: PeerID): T =
+  ## Get all the known metadata of a provided peer.
+  
+  peerBook.book.getOrDefault(peerId)
+
+proc set*[T](peerBook: var PeerBook[T],
+             peerId: PeerID,
+             entry: T) =
+  ## Set metadata for a given peerId. This will replace any
+  ## previously stored metadata.
+  
+  peerBook.book[peerId] = entry
+
+  # Notify clients
+  for handler in peerBook.changeHandlers:
+    handler(peerId, peerBook.get(peerId))
+
+proc delete*[T](peerBook: var PeerBook[T],
+                peerId: PeerID): bool =
+  ## Delete the provided peer from the book.
+  
+  if not peerBook.book.hasKey(peerId):
+    return false
+  else:
+    peerBook.book.del(peerId)
+    return true
+
+####################
+# Address Book API #
+####################
+
+proc add*(addressBook: var AddressBook,
+          peerId: PeerID,
+          multiaddr: MultiAddress) = 
+  ## Add known multiaddr of a given peer. If the peer is not known, 
+  ## it will be set with the provided multiaddr.
+  
+  addressBook.book.mgetOrPut(peerId,
+                             initHashSet[MultiAddress]()).incl(multiaddr)
+  
+  # Notify clients
+  for handler in addressBook.changeHandlers:
+    handler(peerId, addressBook.get(peerId))
+
+#####################
+# Protocol Book API #
+#####################
+
+proc add*(protoBook: var ProtoBook,
+          peerId: PeerID,
+          protocol: string) = 
+  ## Adds known protocol codec for a given peer. If the peer is not known, 
+  ## it will be set with the provided protocol.
+  
+  protoBook.book.mgetOrPut(peerId,
+                           initHashSet[string]()).incl(protocol)
+  
+  # Notify clients
+  for handler in protoBook.changeHandlers:
+    handler(peerId, protoBook.get(peerId))
+
+##################  
+# Peer Store API #
+##################
+
+proc addHandlers*(peerStore: PeerStore,
+                  addrChangeHandler: AddrChangeHandler,
+                  protoChangeHandler: ProtoChangeHandler,
+                  keyChangeHandler: KeyChangeHandler) =
+  ## Register event handlers to notify clients of changes in the peer store
+  
+  peerStore.addressBook.changeHandlers.add(addrChangeHandler)
+  peerStore.protoBook.changeHandlers.add(protoChangeHandler)
+  peerStore.keyBook.changeHandlers.add(keyChangeHandler)
+
+proc delete*(peerStore: PeerStore,
+             peerId: PeerID): bool =
+  ## Delete the provided peer from every book.
+  
+  peerStore.addressBook.delete(peerId) and
+  peerStore.protoBook.delete(peerId) and
+  peerStore.keyBook.delete(peerId)
+
+proc get*(peerStore: PeerStore,
+          peerId: PeerID): StoredInfo =
+  ## Get the stored information of a given peer.
+  
+  StoredInfo(
+    peerId: peerId,
+    addrs: peerStore.addressBook.get(peerId),
+    protos: peerStore.protoBook.get(peerId),
+    publicKey: peerStore.keyBook.get(peerId)
+  )
+
+proc peers*(peerStore: PeerStore): seq[StoredInfo] =
+  ## Get all the stored information of every peer.
+  
+  let allKeys = concat(toSeq(keys(peerStore.addressBook.book)),
+                       toSeq(keys(peerStore.protoBook.book)),
+                       toSeq(keys(peerStore.keyBook.book))).toHashSet()
+
+  return allKeys.mapIt(peerStore.get(it))
diff --git a/tests/testpeerstore.nim b/tests/testpeerstore.nim
new file mode 100644
index 0000000..7eba389
--- /dev/null
+++ b/tests/testpeerstore.nim
@@ -0,0 +1,223 @@
+import
+  std/[unittest, tables, sequtils, sets],
+  ../libp2p/crypto/crypto,
+  ../libp2p/multiaddress,
+  ../libp2p/peerid,
+  ../libp2p/peerstore,
+  ./helpers
+
+suite "PeerStore":
+  # Testvars
+  let
+    # Peer 1
+    keyPair1 = KeyPair.random(ECDSA, rng[]).get()
+    peerId1 = PeerID.init(keyPair1.secKey).get()
+    multiaddrStr1 = "/ip4/127.0.0.1/udp/1234/p2p/QmcgpsyWgH8Y8ajJz1Cu72KnS5uo2Aa2LpzU7kinSupNKC"
+    multiaddr1 = MultiAddress.init(multiaddrStr1).get()
+    testcodec1 = "/nim/libp2p/test/0.0.1-beta1"
+    # Peer 2
+    keyPair2 = KeyPair.random(ECDSA, rng[]).get()
+    peerId2 = PeerID.init(keyPair2.secKey).get()
+    multiaddrStr2 = "/ip4/0.0.0.0/tcp/1234/ipfs/QmcgpsyWgH8Y8ajJz1Cu72KnS5uo2Aa2LpzU7kinSupNKC"
+    multiaddr2 = MultiAddress.init(multiaddrStr2).get()
+    testcodec2 = "/nim/libp2p/test/0.0.2-beta1"
+  
+  test "PeerStore API":
+    # Set up peer store
+    var
+      peerStore = PeerStore.new()
+    
+    peerStore.addressBook.add(peerId1, multiaddr1)
+    peerStore.addressBook.add(peerId2, multiaddr2)
+    peerStore.protoBook.add(peerId1, testcodec1)
+    peerStore.protoBook.add(peerId2, testcodec2)
+    peerStore.keyBook.set(peerId1, keyPair1.pubKey)
+    peerStore.keyBook.set(peerId2, keyPair2.pubKey)
+
+    # Test PeerStore::get
+    let
+      peer1Stored = peerStore.get(peerId1)
+      peer2Stored = peerStore.get(peerId2)
+    check:
+      peer1Stored.peerId == peerId1
+      peer1Stored.addrs == toHashSet([multiaddr1])
+      peer1Stored.protos == toHashSet([testcodec1])
+      peer1Stored.publicKey == keyPair1.pubkey
+      peer2Stored.peerId == peerId2
+      peer2Stored.addrs == toHashSet([multiaddr2])
+      peer2Stored.protos == toHashSet([testcodec2])
+      peer2Stored.publicKey == keyPair2.pubkey
+    
+    # Test PeerStore::peers
+    let peers = peerStore.peers()
+    check:
+      peers.len == 2
+      peers.anyIt(it.peerId == peerId1 and
+                  it.addrs == toHashSet([multiaddr1]) and
+                  it.protos == toHashSet([testcodec1]) and
+                  it.publicKey == keyPair1.pubkey)
+      peers.anyIt(it.peerId == peerId2 and
+                  it.addrs == toHashSet([multiaddr2]) and
+                  it.protos == toHashSet([testcodec2]) and
+                  it.publicKey == keyPair2.pubkey)
+
+    # Test PeerStore::delete
+    check:
+      # Delete existing peerId
+      peerStore.delete(peerId1) == true
+      peerStore.peers().anyIt(it.peerId == peerId1) == false
+
+      # Now try and delete it again
+      peerStore.delete(peerId1) == false
+  
+  test "PeerStore listeners":
+    # Set up peer store with listener
+    var
+      peerStore = PeerStore.new()
+      addrChanged = false
+      protoChanged = false
+      keyChanged = false
+    
+    proc addrChange(peerId: PeerID, addrs: HashSet[MultiAddress]) =
+      addrChanged = true
+    
+    proc protoChange(peerId: PeerID, protos: HashSet[string]) =
+      protoChanged = true
+    
+    proc keyChange(peerId: PeerID, publicKey: PublicKey) =
+      keyChanged = true
+
+    peerStore.addHandlers(addrChangeHandler = addrChange,
+                          protoChangeHandler = protoChange,
+                          keyChangeHandler = keyChange)
+
+    # Test listener triggered on adding multiaddr
+    peerStore.addressBook.add(peerId1, multiaddr1)
+    check:
+      addrChanged == true
+    
+    # Test listener triggered on setting addresses
+    addrChanged = false
+    peerStore.addressBook.set(peerId2,
+                              toHashSet([multiaddr1, multiaddr2]))
+    check:
+      addrChanged == true
+  
+    # Test listener triggered on adding proto
+    peerStore.protoBook.add(peerId1, testcodec1)
+    check:
+      protoChanged == true
+    
+    # Test listener triggered on setting protos
+    protoChanged = false
+    peerStore.protoBook.set(peerId2,
+                            toHashSet([testcodec1, testcodec2]))
+    check:
+      protoChanged == true
+    
+    # Test listener triggered on setting public key
+    peerStore.keyBook.set(peerId1,
+                          keyPair1.pubkey)
+    check:
+      keyChanged == true
+    
+    # Test listener triggered on changing public key
+    keyChanged = false
+    peerStore.keyBook.set(peerId1,
+                          keyPair2.pubkey)
+    check:
+      keyChanged == true
+
+  test "AddressBook API":
+    # Set up address book
+    var
+      addressBook = PeerStore.new().addressBook
+    
+    # Test AddressBook::add
+    addressBook.add(peerId1, multiaddr1)
+    
+    check:
+      toSeq(keys(addressBook.book))[0] == peerId1
+      toSeq(values(addressBook.book))[0] == toHashSet([multiaddr1])
+    
+    # Test AddressBook::get
+    check:
+      addressBook.get(peerId1) == toHashSet([multiaddr1])
+    
+    # Test AddressBook::delete
+    check:
+      # Try to delete peerId that doesn't exist
+      addressBook.delete(peerId2) == false
+
+      # Delete existing peerId
+      addressBook.book.len == 1 # sanity
+      addressBook.delete(peerId1) == true
+      addressBook.book.len == 0
+    
+    # Test AddressBook::set
+    # Set peerId2 with multiple multiaddrs
+    addressBook.set(peerId2,
+                toHashSet([multiaddr1, multiaddr2]))
+    check:
+      toSeq(keys(addressBook.book))[0] == peerId2
+      toSeq(values(addressBook.book))[0] == toHashSet([multiaddr1, multiaddr2])
+  
+  test "ProtoBook API":
+    # Set up protocol book
+    var
+      protoBook = PeerStore.new().protoBook
+    
+    # Test ProtoBook::add
+    protoBook.add(peerId1, testcodec1)
+    
+    check:
+      toSeq(keys(protoBook.book))[0] == peerId1
+      toSeq(values(protoBook.book))[0] == toHashSet([testcodec1])
+    
+    # Test ProtoBook::get
+    check:
+      protoBook.get(peerId1) == toHashSet([testcodec1])
+    
+    # Test ProtoBook::delete
+    check:
+      # Try to delete peerId that doesn't exist
+      protoBook.delete(peerId2) == false
+
+      # Delete existing peerId
+      protoBook.book.len == 1 # sanity
+      protoBook.delete(peerId1) == true
+      protoBook.book.len == 0
+    
+    # Test ProtoBook::set
+    # Set peerId2 with multiple protocols
+    protoBook.set(peerId2,
+                  toHashSet([testcodec1, testcodec2]))
+    check:
+      toSeq(keys(protoBook.book))[0] == peerId2
+      toSeq(values(protoBook.book))[0] == toHashSet([testcodec1, testcodec2])
+
+  test "KeyBook API":
+    # Set up key book
+    var
+      keyBook = PeerStore.new().keyBook
+    
+    # Test KeyBook::set
+    keyBook.set(peerId1,
+                keyPair1.pubkey)
+    check:
+      toSeq(keys(keyBook.book))[0] == peerId1
+      toSeq(values(keyBook.book))[0] == keyPair1.pubkey
+    
+    # Test KeyBook::get
+    check:
+      keyBook.get(peerId1) == keyPair1.pubkey
+    
+    # Test KeyBook::delete
+    check:
+      # Try to delete peerId that doesn't exist
+      keyBook.delete(peerId2) == false
+
+      # Delete existing peerId
+      keyBook.book.len == 1 # sanity
+      keyBook.delete(peerId1) == true
+      keyBook.book.len == 0