Adolescent childbearing has historically been a relatively frequent phenomenon in Mexico and has only recently begun to decline. This study was designed to identify to what extent urban Mexican adolescents, who became pregnant out-of-wedlock and who carried their pregnancy to term, received social support during pregnancy and their emotional response to pregnancy. Data were taken from a longitudinal study of primiparous adolescents (N=172) who gave birth at a public maternity hospital which serves low and lower-middle income women in Mexico City. Assertiveness; depression; quality of emotional support from the adolescent's family of origin, partner's family, and partner; adolescent's emotional reaction to pregnancy; quality of prepregnancy intrafamilial relations; family instability and background variables were assessed. The results indicated: (1) adolescents perceived their families to be quite supportive by the third trimester of pregnancy; (2) adolescent's father's occupation, partner's relationship with family of origin, and quality of couple relationship were significant in regard to emotional support from the partner; (3) only a fifth of the adolescents admitted to feeling badly and were moderately depressed about their situation; and (4) quality of previous intrafamilial relations was the most important factor in adolescent's emotional response. Taken as a whole the results reaffirm the importance of the sociocultural context for understanding the psychosocial meaning of adolescent pregnancy. (ABL)