We report findings from the second phase of a study of co-operative, group-based assessment in Pharmacology for second-year undergraduates at The University of Queensland, Australia. Students (n = 285) enrolled in the 2006 Bachelor of Science degree program completed a group-based assessment task (weighted 10% of their course). Blended teaching strategies and the task design were modified to support group formation and peer teaching. A Jigsaw teaching strategy was adopted to support a co-operative learning task in which groups created and submitted a Notice of Intent (NOI) or mini grant proposal based on the topic of Drug Dependence. Assessment was 7% from the NOI and 3% from an individual quiz. In post-assessment surveys, students reported more favourable attitudes towards assessment in which group members received the same marks than in a pre-teaching survey. Findings from the post-task assessment survey were that most students worked co-operatively around assessment. Most students reported that peer teaching help them to complete their assignment and their individual quiz (3%) more than working in "expert panels" or group-based writing. Overall marks were high: the mean [plus or minus] sd for the group-based NOI was 80 [plus or minus] 13% and for the averaged quiz marks, 73 [plus or minus] 13%. The need for more detailed study of group dynamics is recommended. (Contains 3 figures.)