This study aims to investigate the effect of learning styles, as well as compare the effect of two different variable structure models of learning styles on factors influencing mathematics achievement. The research sample was made up of 508 seventh-grade students. The findings were that the model including learning styles as factors influencing mathematics achievement had a greater coefficient of determination than the one without learning styles; the effect of learning styles treated as exogenous variables had a greater coefficient of determination than learning styles treated as endogenous variables; and the changes in the regression coefficient (b) as well as changes in relations between factors influencing mathematics achievement showed that learning styles was a moderator variable. (Contains 5 tables and 3 figures.)