The following is a copied post from another thread. It offers a list of LACs, including Williams, with well established CS programs:
Professors from the following LACs appear to be among the first to have designed a model CS curriculum for liberal arts colleges. These schools may therefore offer some of the more established programs of their type (listed in approximate order of key upper-level courses offered at least biennially):
Hamilton
Swarthmore
Williams
Grinnell
Allegheny
Vassar
Washington & Lee
Colgate
Denison
Amherst
Bowdoin
(Sources: The Liberal Arts Computer Science consortium and table provided by ucbalumnus.)
This link will take you to the original thread: