In some laboratory rodents, males’ brains and behavior become less sensitive to the organizing effects of androgens across the time window surrounding puberty. Later puberty in human males has also been associated with less male-typical psychology and behavior, such as lower performance on mental rotation tasks and lower risk of substance abuse and delinquency. Here, we propose that life history (LH) theory provides a useful theoretical framework for understanding such relationships between pubertal timing and phenotypic masculinization. Because a faster male LH strategy emphasizes mating over parenting, earlier puberty may lead more generally to greater masculinization of traits that increase in sexual dimorphism at puberty and function in mating competition. In other words, we suggest that decreasing sensitivity to androgens represents a proximate mechanism that facilitates the development of mating-related adaptations in men with fast LH strategies. We tested this hypothesis in 153 men. Consistent with our hypothesis, earlier recalled pubertal timing predicted greater adult male body mass index, facial dominance, biceps circumference, and, to a lesser degree, systemizing and mental rotation ability. Some sexually dimorphic traits that were unrelated to pubertal timing in our data may have been less relevant to our male ancestors’ mating success and hence to a fast LH strategy.