diff --git a/spacy/vocab.pxd b/spacy/vocab.pxd
new file mode 100644
index 000000000..89e22ed25
--- /dev/null
+++ b/spacy/vocab.pxd
@@ -0,0 +1,38 @@
+from libcpp.vector cimport vector
+
+from preshed.maps cimport PreshMap
+from cymem.cymem cimport Pool
+from murmurhash.mrmr cimport hash64
+
+from .structs cimport Lexeme, TokenC, UniStr
+from .typedefs cimport utf8_t, id_t, hash_t
+from .strings cimport StringStore
+
+
+cdef union LexemesOrTokens:
+    const Lexeme* const* lexemes
+    TokenC* tokens
+
+
+cdef struct _Cached:
+    LexemesOrTokens data
+    bint is_lex
+    int length
+
+
+cdef inline void slice_unicode(UniStr* s, Py_UNICODE* chars, int start, int end) nogil:
+    s.chars = &chars[start]
+    s.n = end - start
+    s.key = hash64(s.chars, s.n * sizeof(Py_UNICODE), 0)
+
+
+cdef class Vocab:
+    cpdef public get_lex_props
+    cdef Pool mem
+    cpdef readonly StringStore strings
+    cdef vector[Lexeme*] lexemes
+
+    cdef const Lexeme* get(self, Pool mem, UniStr* s) except NULL
+    
+    cdef PreshMap _map
+  
diff --git a/spacy/vocab.pyx b/spacy/vocab.pyx
new file mode 100644
index 000000000..6c19d277e
--- /dev/null
+++ b/spacy/vocab.pyx
@@ -0,0 +1,127 @@
+from libc.stdio cimport fopen, fclose, fread, fwrite, FILE
+
+from os import path
+
+from .lexeme cimport EMPTY_LEXEME
+from .lexeme cimport init as lexeme_init
+
+
+cdef class Vocab:
+    '''A map container for a language's Lexeme structs.
+    
+    Also interns UTF-8 strings, and maps them to consecutive integer IDs.
+    '''
+    def __init__(self, object get_props):
+        self.mem = Pool()
+        self._map = PreshMap(2 ** 20)
+        self.strings = StringStore()
+        self.lexemes.push_back(&EMPTY_LEXEME)
+        self.get_lex_props = get_props
+
+    def __len__(self):
+        return self.lexemes.size()
+
+    cdef const Lexeme* get(self, Pool mem, UniStr* string) except NULL:
+        '''Get a pointer to a Lexeme from the lexicon, creating a new Lexeme
+        if necessary, using memory acquired from the given pool.  If the pool
+        is the lexicon's own memory, the lexeme is saved in the lexicon.'''
+        cdef Lexeme* lex
+        lex = <Lexeme*>self._map.get(string.key)
+        if lex != NULL:
+            return lex
+        if string.n < 3:
+            mem = self.mem
+        cdef unicode py_string = string.chars[:string.n]
+        lex = <Lexeme*>mem.alloc(sizeof(Lexeme), 1)
+        lex[0] = lexeme_init(self.lexemes.size(), py_string, string.key, self.strings,
+                             self.get_lex_props(py_string))
+        if mem is self.mem:
+            self._map.set(string.key, lex)
+            while self.lexemes.size() < (lex.id + 1):
+                self.lexemes.push_back(&EMPTY_LEXEME)
+            self.lexemes[lex.id] = lex
+        else:
+            lex[0].id = 1
+        return lex
+
+    def __getitem__(self,  id_or_string):
+        '''Retrieve a lexeme, given an int ID or a unicode string.  If a previously
+        unseen unicode string is given, a new Lexeme is created and stored.
+
+        This function relies on Cython's struct-to-dict conversion.  Python clients
+        receive a dict keyed by strings (byte or unicode, depending on Python 2/3),
+        with int values.  Cython clients can instead receive a Lexeme struct value.
+        More efficient Cython access is provided by Lexicon.get, which returns
+        a Lexeme*.
+
+        Args:
+            id_or_string (int or unicode): The integer ID of a word, or its unicode
+                string.  If an int >= Lexicon.size, IndexError is raised.
+                If id_or_string is neither an int nor a unicode string, ValueError
+                is raised.
+
+        Returns:
+            lexeme (dict): A Lexeme struct instance, which Cython translates into
+                a dict if the operator is called from Python.
+        '''
+        if type(id_or_string) == int:
+            if id_or_string >= self.lexemes.size():
+                raise IndexError
+            return self.lexemes.at(id_or_string)[0]
+        cdef UniStr string
+        slice_unicode(&string, id_or_string, 0, len(id_or_string))
+        cdef const Lexeme* lexeme = self.get(self.mem, &string)
+        return lexeme[0]
+
+    def __setitem__(self, unicode uni_string, dict props):
+        cdef UniStr s
+        slice_unicode(&s, uni_string, 0, len(uni_string))
+        # Cast through the const here, since we're allowed to change our own
+        # Lexemes.
+        lex = <Lexeme*><void*>self.get(self.mem, &s)
+        lex[0] = lexeme_init(lex.id, s.chars[:s.n], s.key, self.strings, props)
+
+    def dump(self, loc):
+        if path.exists(loc):
+            assert not path.isdir(loc)
+        cdef bytes bytes_loc = loc.encode('utf8') if type(loc) == unicode else loc
+        cdef FILE* fp = fopen(<char*>bytes_loc, 'wb')
+        assert fp != NULL
+        cdef size_t st
+        cdef hash_t key
+        for i in range(self._map.length):
+            key = self._map.c_map.cells[i].key
+            if key == 0:
+                continue
+            lexeme = <Lexeme*>self._map.c_map.cells[i].value
+            st = fwrite(&key, sizeof(key), 1, fp)
+            assert st == 1
+            st = fwrite(lexeme, sizeof(Lexeme), 1, fp)
+            assert st == 1
+        st = fclose(fp)
+        assert st == 0
+
+    def load(self, loc):
+        if not path.exists(loc):
+            raise IOError('Lexemes file not found at %s' % loc)
+        cdef bytes bytes_loc = loc.encode('utf8') if type(loc) == unicode else loc
+        cdef FILE* fp = fopen(<char*>bytes_loc, 'rb')
+        assert fp != NULL
+        cdef size_t st
+        cdef Lexeme* lexeme
+        cdef hash_t key
+        i = 0
+        while True:
+            st = fread(&key, sizeof(key), 1, fp)
+            if st != 1:
+                break
+            lexeme = <Lexeme*>self.mem.alloc(sizeof(Lexeme), 1)
+            st = fread(lexeme, sizeof(Lexeme), 1, fp)
+            if st != 1:
+                break
+            self._map.set(key, lexeme)
+            while self.lexemes.size() < (lexeme.id + 1):
+                self.lexemes.push_back(&EMPTY_LEXEME)
+            self.lexemes[lexeme.id] = lexeme
+            i += 1
+        fclose(fp)