The present study evaluates cooperatively structured vocabulary learning activity used in a beginning JFL class. It also discusses social and affective aspects of such group learning. The study is framed by theoretical and empirical studies in the fields of SLA and cooperative learning. Cooperative structured group work is believed to facilitate SLA by providing scaffolding among learners and also a more constructive social and affective environment for group participant. A class of beginning JFL students learned sets of vocabulary in cooperatively structured groups using cooperative activity that was adapted for language learners from Kagan’s (1994) Numbered Head Together. Students then took a quiz every time after engaging in the activity, and the results were compared with those obtained from students in the other class who learned the same vocabulary using a more traditional, teacher-fronted approach. Although an analysis of the quiz scores revealed no statistical differences between the classes, student opinion questionnaires revealed that most students felt that group work helped to create a favorable social and affective environment for learning.