Promoting mathematical creativity is an important aim of mathematics education, which may be promoted by engaging students with open-ended tasks. Most studies of students' creativity have investigated the creativity of students working individually. This study concerns the mathematical creativity of students working as individuals as compared with those working in groups. Participants were 92 post--high school students, separated into two heterogeneous classes. Both classes engaged with the same three geometric open-ended tasks. For the first two tasks, one class worked individually, while the second worked in small groups of four to six students. For the third task, all students worked individually. Results were analyzed in terms of fluency, flexibility, and originality. No significant differences were found between classes for fluency and flexibility on the first task. However, for the second and third tasks, there were greater fluency and flexibility among those who worked or had worked in groups. For all three tasks, no significant differences between the classes were found regarding originality.