A young person's first consensual sexual intercourse experience is often a remarkable and memorable experience. However, little systematic information exists regarding contextual factors of first intercourse, the affective salience of the experience, possible effects on sexual attitudes and beliefs, and subsequent sexual development and adjustment. This retrospective study aimed to examine these in a sample of 475 young adults. Overall, young men and women experienced intercourse for the first time around age 17, were in a committed relationship, and reported positive affective responses. Affective reactions to the first sexual intercourse experience, sexual self-efficacy, sexual aversion, and age at first intercourse affected individuals' current sexual adjustment; however, only sexual self-efficacy mediated between first intercourse and current sexual adjustment in young men and women. Older age at first intercourse was associated with less sexual self-efficacy and lower current sexual adjustment for women. This study provides initial data to suggest that the first sexual intercourse experience significantly impacts current sexual adjustment by affecting beliefs about sexual self-efficacy.