Although active learning works, promoting it in large undergraduate science classes is difficult. Here, three students (F. Naji, L. Salci, and G. Hoit) join their teacher (P. K. Rangachari) in describing one such attempt. Two cohorts in a first-year undergraduate biology course explored the molecular underpinnings of human misbehavior. Students were divided into 18 groups and randomly allotted to deal with one of the four deadly sins: sloth, gluttony, lust, and wrath. Students were expected to read primary sources to devise molecular ways to counter these sins. Group progress was monitored over the 12-wk period by the preceptor (P. K. Rangachari) at scheduled intervals. A single randomly selected student was questioned about the work done, and future directions were provided by the preceptor. At the end of the term, randomly selected students defended their group's approaches to the entire class. A final written report was graded. The following multiple target molecules were considered for each sin: gluttony (cholecystokinin, ghrelin, GABA, leptin, peptide YY, neuropeptide Y, and the melanocortin 4 receptor); sloth (dopamine, glutamate, GABA, and orexin); wrath (serotonin, GABA, glutamate, and corticotropin-releasing hormone receptor 2); and lust (prolactin, testosterone, oxytocin, dopamine, and estrogen). Students noted that the project provided a valuable learning experience, and the random selection approach gave students a greater sense of responsibility to their group. The project helped students hone their skills at searching, synthesizing, sharing, and presenting information, fostered group interactions, and provided a solid knowledge base for subsequent courses. (Contains 2 tables and 1 figure.)