Sources of mathematics self-efficacy (SMS), which foster the development of self-efficacy belief, can develop differently in students with different cognitive characteristics. The objective of this study was to compare SMS of gifted and nongifted students after controlling for mathematics achievement. Participants of the study consisted of 106 gifted and 118 non-gifted students in high schools. The study was a causal-comparative design. The data was collected through the Sources of Mathematics Self-Efficacy Scale, and students' self-reported previous fall mathematical grades. The results of the study revealed that after controlling for mathematics grades, while SMS of gifted children sharply decreased, SMS in the nongifted group slightly increased. In addition, only vicarious experience di...