Few empirical studies focus on how boys respond to puberty. This paper presents the results of a questionnaire and interview survey of 36 white middleclass adolescent male camp counselors (mean age, 18.4 years) that addressed pubertal changes and first ejaculation (“semenarche”). It is a descriptive and hypothesis generating study. The first ejaculation, biologically significant in sexual and reproductive functioning, was found to be psychologically meaningful but socially invisible. The mean age at semenarche was 12.9 years. All of the boys in the group had sex education in school, yet many felt unprepared for their first ejaculation, which occurred earlier than they expected and before formal education. Those who felt prepared expressed more positive feelings and coped better. Common responses to semenarche included surprise, curiosity, pleasure, and confusion. Most subjects did not tell anyone that this event occurred and many boys initially confused ejaculation and urination. The association of the first ejaculation with sexuality makes it a charged event. Psychosocial and developmental difficulties in sexual education for young males are noted.