The present study investigated the nomological validity of the Amotivation Inventory-Physical Education (Shen, Wingert, Li, Sun, & Rukavina, 2010b) scores by examining the associations of ability, effort, value, and task characteristics amotivation beliefs with self-determination theory variables. Data were collected from 401 fifth- and sixth-grade students, 416 middle-school students, and 401 high-school students. After providing support for the correlated four-factor structure, the hierarchical structure, internal consistency, and composite reliability of the Amotivation Inventory-Physical Education scores, large negative correlations emerged with perceived autonomy support by the PE teacher; needs for autonomy, competence, and relatedness; identified regulation; intrinsic motivation; and students' subjective vitality. Strong positive correlations were obtained with unidimensional amotivation and external regulation, and weak correlations were obtained with introjected regulation. Also, multidimensional amotivation beliefs partially mediated the relationship between the need for autonomy and subjective vitality. The results provided support for the nomological aspect of construct validity of the Amotivation Inventory-Physical Education scores. (Contains 5 tables and 4 figures.)