This study aimed to identify the factors that predict success in a teamwork task with secondary students. The following factors, which have been established by research as key elements in the resolution of teamwork task in a cooperative way, were treated as the independent variables: gender composition, group objectives, distribution of roles, interaction patterns, goal orientation, social atmosphere, reciprocal support, effective time focused on work and group self assessment. The study consisted of 87 triads (N = 261). The groups were asked to write an expository text on how to measure fever after having read three complementary source texts. The correct integration of the ideas was the dependent variable. The factors best predicted successes were group self assessment; the perception on effective use of time; a positive social atmosphere, especially at the beginning of the interaction; and a predominance of girls in the groups.