We tested predictions about psychosocial factors in the onset of menarche using data from a longitudinal study of 16-year-old girls. Belsky, Steinberg, and Draper have proposed a model that seeks to explain individual differences in maturational timing in terms of stressful childhood experiences. Their model hypothesizes that (1) individuals who grow up under conditions of family stress (2) experience behavioral and psychological problems which (3) provoke earlier reproductive readiness. In this study, the effect of family stressors on menarche was mediated by neither behavior problems nor weight, contrary to the predictions. However, the most provocative proposition advanced by Belsky et al. received empirical support. Family conflict and father absence in childhood predicted an earlier age of menarche, and these factors in combination with weight showed some evidence of an additive influence on menarche. A genetic inheritance model may provide a more parsimonious account of these data than does a conditional adaptation model derived from sociobiology.