Home environments have been linked to cognitive development and academic performance, with suggestions that family factors exert more influence on language and literacy learning than on mathematics achievement. This study's purpose was to learn how selected family factors might be differentially related to primary grade achievement in reading and mathematics in children from low-income families. Family factors were contrasted in first graders who scored in the highest and lowest quartile on Woodcock-Johnson tests of reading and mathematics. Participants were 167 children from low-income families (80% were African American) in a Head Start Transition Demonstration program, which provides low-income families with elementary school children the same support as received in Head Start. Children who did well in reading were from homes with higher scores on the Home Screening Questionnaire, were from smaller families, had better educated mothers, and were rated as more healthy. Children who did better in math were from families who scored high on the questionnaire and tended to have more contact with their fathers. Regression analyses indicated that transition treatment interacted with family size and showed a trend toward interacting with the questionnaire scores to predict reading scores summed across kindergarten and first grade. Treatment interacted with maternal education to predict similarly summed mathematics scores. Quality of the home environment independently predicted math scores. The conclusion was that children's learning is heavily influenced by home environment. Contains 26 references. (Author/BGC)