This study assessed the impact of family childhood income on completed years of schooling using fixed effects techniques to eliminate biases associated with omission of unmeasured family characteristics. It also examined the importance of timing of family income, estimating models that related years of completed schooling to average levels of parental income in early childhood, early middle childhood, preadolescence, and adolescence. Data came from the Panel Study of Income Dynamics (PSID), a longitudinal household survey. This study used sibling data on 1,364 families with children born between 1968-76 and present in the PSID between birth and age at least 20 years. The outcome measure, completed years of schooling, was examined when the child was age 20 years. The income measure was the total pre-tax income of all family members, inflated to 1993 price levels. Results indicated that family income during early childhood positively impacted children's educational attainment. The magnitude of the effect suggested that a 2.7-fold increase in parental income when the child was age 0-4 years led to an increase of about half a year of schooling. Income during adolescence had a positive, but less robust, effect. (Contains 21 references.) (SM)