The Mexican Hermit (Phaethornis mexicanus) is endemic to west-central Mexico, with 2 recognized subspecies, P. mexicanus mexicanus and P. mexicanus griseoventer. This hummingbird forms leks, where males are territory holders and females visit them to choose a mate. Only the female provides parental care to the progeny. We observed P. mexicanus griseoventer leks over different breeding seasons at 3 sites in the understory of tropical dry forest and subtropical moist lowland forests. The displays of males consisted of monosyllabic calls from perched individuals and, when a female appeared nearby, slow-speed tail movements and hover flying in front of that female. The females visited the leks and moved around, perching in the territories of different males. In addition, we monitored one nest from egg-laying to fledging of the young in Hacienda Las Tres Carmelitas. We also characterized the nest site and the materials used in nest construction. For 20 d in July and August, the female incubated 2 eggs and hatched 2 chicks. The young left the nest 31 d after hatching. We inferred that the Mexican Hermit moves between the cloud forest (790 m asl) and the pine-oak forest (1080 m asl) to obtain nest material and food. Our observations of lekking and nesting behavior suggest that breeding in P. m. griseoventer extends from February (leks) to at least mid-October (nesting).