To have an uninterrupted growth performance of participation banks may be only possible by sustainable development strategies that are consistent with market dynamics. Investigating the reasons why customers prefer these institutions, what their expectations are, and analyzing the data obtained from these researches are critical in developing strategies. Comprehensive field research covering all provinces of Turkey which aims to determine the reasons for customer preference of participation banks may provide policy implications for the policymakers. As the first step towards carrying out such research, it was aimed to investigate the reasons for preferring participation banks in Kocaeli province. In the study, the required data were collected and analyzed with the help of quantitative and qualitative research methods. Firstly, an in-depth interview method was applied in qualitative research to obtain the data from 12 customers working with participation banks in a long period of time. Secondly, the questionnaire method was used to collect data from a wider customer sample regarding the factors that are important for working with the participation banks. 407 questionnaires were analyzed and interpreted. 5 main factors, such as religious factors, service quality variables, social environment effect, financial variables, and marketing mix variables were found to be effective in preferring participation banks. The findings of this exploratory study are consistent with the related literature and it is expected to guide to future studies.