The construct of ability conceptions plays a critical role in children's motivation and achievement behaviors in education, including physical education. Valid and reliable measures of this construct are essential to advance our knowledge of children's ability conceptions and related cognitive, affective, and behavioral outcomes. From a measurement point of view, this article discusses the construct of ability conceptions from two major theoretical perspectives in terms of differences and commonalities. It also offers insights to further improve the psychometric properties of ability conceptions measures.