Technology Acceptance Model (TAM) is widely applied to explain how users come to adopt a new technology. Motivated by the need to have a better understanding of the rapid growth of fitness applications (apps) on smartphones, this study tests an extension of the TAM model through explaining how social influence and application characteristics affect college students’ behavioral intention of downloading fitness applications to their smartphones. Based on a survey and a series of regression analyses, the results confirm the effects of two major determinants—perceived usefulness and perceived ease of use—on users’ attitude toward using fitness apps. In addition, the findings show that electronic word of mouth (eWOM) and application characteristics significantly influence downloading of fitness apps. Finally, the results underline the crucial role of apps functional features. By adding external factors, the proposed research model fits in the context of fitness apps, and fills the literature gap by identifying how to motivate individuals to download fitness apps. The study provides researchers and marketers with empirical evidence about college students’ reasons for selection of fitness apps.