Despite changes, gender differences in math and science continue to exist in some countries. We examined whether the actiotopes of boys and girls at the high school level in math and science differed and the extent to which (a) their actiotope components, (b) the progressive development of their actiotopes (dynamic perspective), and (c) the co-adaptation of their actiotopes (systems perspective) function as predictors for girls' and boys' achievements and confidence in one's own abilities in math and science. To answer these questions, we examined girls and boys (N?=?361) in Canada, the Czech Republic, and Germany with a questionnaire. The results suggest that girls are less effective at progressively developing their actiotopes in the fields of math and science and that modifications in their actiotopes were less well balanced by stabilizing forces. Independent of gender, the actiotope aspects considered here are suited to predicting achievements and confidence in one's own abilities in math and science.