In this paper, we present results from an online survey with 1,510 participants and an interview study with 31 participants on (secure) mobile instant messaging. Our goal was to uncover how much of a role security and privacy played in people's decisions to use a mobile instant messenger. In the interview study, we recruited a balanced sample of IT security experts and non-experts, as well as an equal split of users of mobile instant messengers that are advertised as being more secure and/or private (e.g., Threema) than traditional mobile IMs. Our results suggest that peer influence is what primarily drives people to use a particular mobile IM, even for secure/private IMs, and that security and privacy play minor roles.