In this study, the effect of mathematics teacher candidates' locus of control on math anxiety was tested, along with the effects of gender, achievement and class level moderators. The study was carried out according to a causal design in which locus of control was taken as an independent variable, while math anxiety was taken as the dependent variable, and gender, achievement and class levels were considered as moderator variables. The participants were 402 students from three different state universities in Turkey who were selected using a combination of convenience and purposive sampling. Data were collected from the participants using the Locus of Control Scale (LCS) and the Math Anxiety Rating Scale-Short Version (MARS-SV). A path analysis was then used to provide a combination of measurement error in both latent and observed variables. The results of the path analysis revealed that the participants' locus of control positively affected math anxiety. Furthermore, the moderator analysis showed that this effect was higher in males and in groups with lower achievement scores. Finally, a significant positive correlation was found between the external locus of control and the total and sub-scale scores of math anxiety.