Now that people on mobile devices can easily choose their mode of communication (e.g., voice, text, video), survey designers can potentially allow respondents to answer questions in whatever mode they find momentarily convenient given their circumstances or that they chronically prefer. We conducted an experiment to explore how mode choice affects response quality, participation, and satisfaction in smartphone interviews. A total of 1,260 iPhone users were contacted on their iPhones by either a human or an automated interviewer via voice or SMS text. This created four modes: Human Voice, Human Text, Automated Voice, and Automated Text. In half of the initial contacts, respondents were required to choose their interview mode (which could be the contact mode); in the remaining half, the mode was simply assigned. Respondents who chose their interview modes provided more conscientious (fewer rounded and non-differentiated) answers, and they reported greater satisfaction with the interview. Although fewer respondents started the interview when given a choice of mode, a higher percentage of Mode Choice respondents who started the interview completed it. For certain mode transitions (e.g., from automated interview modes), there was no reduction in participation. The results demonstrate clear benefits and relatively few drawbacks resulting from mode choice, at least among these modes and with this sample of iPhone users, suggesting that further exploration of mode choice and the logistics of its implementation is warranted.