The present study addressed girls' (N=127) early numerical and spatial reasoning skills, within the context of a critical environment in which these cognitive skills develop, namely their homes. Specifically, proximal links between distal family socioeconomic conditions and first-grade girls' arithmetic and spatial skills were examined (mean age=6.72 years; SD=0.34). The proximal roles of two factors were considered: the general learning characteristics of girls' homes, and the kinds of math and spatial learning activities in which girls participated. General quality of the home learning environment and specific math activities mediated the relation between family socioeconomics and girls' arithmetic skills. In contrast, socioeconomics and home learning experiences were related to girls' spatial skills indirectly only through their verbal skills; spatial activities were not proximal predictors of spatial skills. For both arithmetic and spatial skills, mothers' spatial skills were a strong predictor. Future research and intervention implications of these findings are discussed. (Contains 4 tables and 3 figures.)