Data collected in 1976 by the National Assessment of Educational Progress (NAEP) were analyzed by using a path analysis of clusters of variables combined into single composite variables. Investigated were the relative importance and effect of three clusters of variables (home environment variables, community and school environment variables, and school instructional variables) on educational achievement in the areas of mathematics, political knowledge, and socio-political attitudes. The effect of school on learning was substantially larger than the effect of type of school and school program and tended to be quite high relative to the effect of home on learning. (MP) Primary type of information provided by report: Results (Background Variables).