Psychomotor reminiscence was studied in relation to endogenous variations in estrogenic hormone levels. Forty-three young adult females monitored their menstrual cycles for two replications, then reported for testing on Day 2, 8, or 14 of their cycles. Results showed significantly higher reminiscence and postrest performance on Day 14 (high estrogen) than on the other days (low estrogen). The well-known response activation properties of the estrogens may fulfill one of Hull’s (1943) conditions for the generation of reactive inhibition (Ir), of which reminiscence is regarded as a measure. Since female levels of estrogen are substantially higher than male levels, even at the nadirs of their estrogen cycles, one arrives at a plausible account of the often-demonstrated female dominance in psychomotor reminiscence proclivities.