UNLABELLED: Mating and other behaviors emerge during adolescence through the coordinated actions of steroid hormone signaling throughout the nervous system and periphery. In this study, we investigated the transcriptional dynamics of the medial preoptic area (MPOA), a critical region for reproductive behavior, using single-cell RNA sequencing (scRNAseq) and ONE SENTENCE SUMMARY: Single cell RNA sequencing reveals how adolescent sex hormones sculpt hypothalamic cell types required for mating behavior.