Recent research in second language acquisition has focused on the effects of group work on learning by examining various factors (i.e., motivation, age, task, gender differences, etc.). One particular factor that has not been heavily investigated is interlocutor familiarity, which is at the forefront of the present study. Two separate classes (in both classes, n = 23) of introductory Spanish (Spanish 1002) at Temple University were used in the present study. Subjects in Class #1 worked with the same partner of their choosing throughout the semester. Subjects in Class #2 did not repeat partners and were assigned a different partner during each group task throughout the semester. All subjects received the same treatment. Part of this treatment consisted of two separate lessons on slang terms from Spain that included creative group work assignments. Learners' written group work assignments were collected for analyses. To examine and compare learners' retention in each of the classes, a total of three slang retention tests were administered. All three tests were individual assignments. The first slang test (Slang 1 Immediate Test) was administered on the second class session following Slang Lesson #1 and consisted of slang terms from Slang Lesson #1. The second slang test (Slang 2 Immediate Test) was administered on the second class session following Slang Lesson #2 and consisted of slang terms from Slang Lesson #2. At the end of the semester the third slang retention test (Final Slang Retention Test) was comprehensive, consisting of the slang terms from both lessons. Results suggested that learners' overall retention was higher in Class #1 than in Class #2. At the end of the semester, a Group Work Attitudes Questionnaire was administered and revealed that Class #1 viewed interlocutor familiarity and group work as positive, whereas Class #2 viewed group work as problematic. In addition, learners in Class #1 produced larger quantities of text in the group work assignments and engaged in more slang play than Class #2. The findings suggest the need to further investigate the effects of interlocutor familiarity on language acquisition. / Spanish