The impact of grades on daily self-esteem, affect, and identification with major was examined in a sample of 122 male and female students majoring in engineering and psychology. Self-esteem, affect, and identification with major increased on days students received good grades and decreased on days they received poor grades; basing self-esteem on academic competence moderated the effect of bad grades. Bad grades led to greater drops in self-esteem but not more disidentification with the major for women in engineering. Instability of self-esteem predicted increases in depressive symptoms for students initially more depressed.