This study of all high school graduates of June, 1966, in San Diego, California, supports the conclusion that college entry is affected by the socio-economic contexts of students' neighborhoods and schools through the intervening influence upon manifest ability, as indicated by I.Q. scores and grade point averages, and upon college aspirations. Contrary to initial expectations, it was found that the association between neighborhood and school socio-economic contexts and college entrance tended to disappear when controlled on indices of ability and aspiration. In other words, these data indicate that with equal manifest ability and aspiration indications, rates of college entry tend to be more or less equal among those from differing socio-economic contexts. However, these data also indicate that differing socio-economic contexts are associated with differing distributions on ability manifestations and college aspirations, which in turn is associated with differing rates of college entry. (Author)