This study investigates if collaboration and the level of heterogeneity between collaborating partners' problem-solving scripts can influence the extent to which pre-service teachers engage in evidence-based reasoning when analyzing and solving pedagogical problem cases. We operationalized evidence-based reasoning through its content and process dimensions: (a) to what extent pre-service teachers refer to scientific theories or evidence of learning and instruction (content level) and (b) to what extent they engage in epistemic processes of scientific reasoning (process level) when solving pedagogical problems. Seventy-six pre-service teachers analyzed and solved a problem about an underachieving student either individually or in dyads. Compared with individuals, dyads of pre-service teachers referred less to scientific content, but engaged more in hypothesizing and evidence evaluation and less in generating solutions. A greater dyadic heterogeneity indicated less engagement in generating solutions. Thus, collaboration may be a useful means for engaging preservice teachers in analyzing pedagogical problems in a more reflective and evidence-based manner, but pre-service teachers may still need additional scaffolding to do it based on scientific theories and evidence. Furthermore, heterogeneous groups regarding the collaborating partners' problem-solving scripts may require further instructional support to discuss potential solutions to the problem.