Work values, or the qualities and rewards that one desires from work, are considered to be important determinants of career decision making and exploration during adolescence. A study was conducted to investigate age-based continuities and discontinuities in the structure of work values in a cross-sectional sample of 679 students in grades 7-12. It was hypothesized that the structure of work values would not be continuous across the grade levels, and that the discontinuities would reflect a normative pattern of increased differentiation. Work values were measured with the Work Aspect Preference Scale (WAPS). Confirmatory factor analysis was the primary data analytic strategy. The purpose of the analysis was to test for factor invariance of the WAPS scales across gender and grade levels. The model depicting configural factor invariance across grade levels was rejected, and in general, the structure was found to be more differentiated in the higher grade levels than in the lower grade levels. Females also tended to evidence greater differentiation than males. The findings suggest that the development of work values during adolescence is characterized by the progression toward greater differentiation. (Author/KC)