This case study of a year 8 class explores if collaborative learning could help year 8 pupils develop both their moral reasoning skills and increase their retention of RE subject knowledge. The research assumes that knowledge is epistemologically grounded in a ‘knowledge rich’ curriculum with ‘moral reasoning’ understood through a Kohlbergian framework of moral development, in contrast to postmodern or character-based approaches. Through observation of pupils’ engagement with collaborative learning, analysis of group and individually produced answers, and qualitative analysis of Kohlbergian style moral dilemmas to investigate the extent to which pupils engaged with collaborative learning tasks, retained knowledge of RE subject knowledge (Christian ethics) and developed their moral reasoning skills. Overall, findings suggest that collaborative learning could help some pupils learn and retain subject knowledge. However, collaborative learning was largely ineffectual at helping pupils develop their moral reasoning skills, with pupils limited to preconventional and conventional stages of moral reasoning.