Longitudinal examination of early adolescent girls' premenarcheal expectations and postmenarcheal experiences of positive and negative menstrual related changes. Ratings of 14 positive and negative changes were made by 80 girls on three occasions: (1) in grade 6 when girls were premenarcheal, (2) at the test occasion within six months after each girls' own menarche, and (3) in grade 9 when girls were postmenarcheal. Premenarcheal girls rated expectations of changes, and postmenarcheal girls rated experiences of changes, for both premenstrual and menstrual phases. Girls also rated preparation for, and emotional response to, menarche and mothers' helpfulness on the first two occasions. Ratings for positive and negative changes were at similar levels premenarcheally and decreased at menarche; once menstruation became established, ratings of negative changes increased while those of positive changes decreased. Ratings for negative changes were higher in the menstrual phase, while ratings for positive changes were higher in the premenstrual phase. Premenarcheal expectations of changes contributed to the prediction of menarcheal experiences of changes. Premenarcheal expectations and menarcheal experiences, along with anticipated emotional response to menarche, contributed to the prediction of longer-term experience of negative changes; menarcheal experiences, along with preparation for and emotional response to menarche, contributed to the prediction of longer-term experience of positive changes. Both expectations about, and initial experiences of, menstrual cycle-related changes were associated with longer-term menstrual experiences. The different outcomes for positive and negative changes have implications for menstrual socialization, and provide the basis for some optimism about facilitating a more complex and multidimensional understanding of menstruation.