While much second language acquisition research has focused on characteristics of in-class language study, little is known about the characteristics and effectiveness of out-of-class language study. This exploratory study addresses this gap by analyzing questionnaire data from 707 adult students enrolled in intensive (6-16 months) language study regarding preferred out-of-class activities and time spent on these activities in relation to language outcome scores (e.g., Defense Language Proficiency Test [DLPT] and Oral Proficiency Interview [OPI] scores), while also controlling for background variables such as language aptitude. Regarding time spent on out-of-class activities, mixed-effects linear regression modeling (approximately 400 students) showed that more time spent on assigned and unassigned course study was associated with lower end-of-course language outcomes, and less time spent was associated with higher language outcomes. Engagement in some target-language activities, however, such as using social media to interact in the target language (e.g., chat) showed positive relationships with achieving overall language proficiency. The findings offer important insight into the complex relationships between time spent on out-of-class study, target language activities, background variables, and course outcomes. [Funding was provided by the United States Government.]