The purpose of this paper is to examine the role of media literacy and attitudes towards socioscientific issues as two major predictors of informal reasoning. A sample of 208 preservice science teachers completed an open-ended informal reasoning questionnaire on hydroelectric power plant issue, media literacy level determination scale, and attitudes towards socio-scientific issues scale. In this study, descriptive research method was used. We used both qualitative and quantitative methods to analyze the data. Results indicated that the participants frequently used ecological-oriented arguments. The participants least used health-oriented arguments. Regarding reasoning qualities, the participants typically created supportive arguments, rather than counterarguments and rebuttals. Confirmatory factor analysis revealed validity and reliability evidence consistent with previous research. Multiple regression analyses revealed that perceived level of media literacy predicted informal reasoning. However, attitudes towards socioscientific issues did not explain informal reasoning. We offer implications for science teacher education programs.