Mobile financial services are said to promote inclusion. However, only 7.6 per cent of Kenyans have ever saved on an M-PESA account. This paper uses a novel, three-step probit analysis to identify the socio-demographic characteristics of, successively, respondents who do not have access to a SIM card, have access to a SIM but do not have an M-PESA account, and, finally, have an account but do not save on it. We find that those who are left behind are predominantly those who would benefit most from formal saving, namely the poor, the non-educated, and, in the final step, also women.