Data on the work experiences of children and early adolescents are scarce. Preliminary evidence suggests, however, that very young workers - especially poor, minority youth - may be at risk for adverse work-related effects, including on-the-job injuries. Pre-existing work-related data from 7,420 South Texas middle school students were analyzed according to the specific aims of the study: to determine the prevalence of employment among middle school youth; to document the prevalence of work-related injury in middle schoolers; to describe the demographic characteristics of working middle school students and injured workers; to describe quality of life issues associated with working and work-related injuries; and to determine environmental factors and behavioral factors associated with work-related injuries. Results indicated that 25% of employed students reported having ever experienced an occupational injury. Of the injured, 30% required medical help. A dose response effect was observed where increasing weekly work hours were significantly related to work injury. Types of jobs associated with work-related injury were restaurant work, agriculture, construction, and retail work. Restaurant work was associated with injury requiring medical help. The overall prevalence of employment was 56%. Three-quarters of workers employed 1-10 hours weekly. Employed students worked an average of 8 hours weekly. Middle school students were more likely to work in childcare and yard work than in other types of jobs. About half of students reported working to earn spending money. Working longer hours weekly was associated with using several substances, decreased sleep, increased stress and frequency of having headaches, and dissatisfaction with amounts of leisure time. Working more than 10 hours weekly was also correlated with poorer school performance and school disengagement. An important addition to the literature is our finding that Hispanic middle schoolers experience fewer job-related injuries compared to whites, but are at a greater risk of more serious injury than whites. Also, we substantiated the findings of other occupational injury studies of older youth regarding the prevalence of youth injury and several subgroup differences within that prevalence, i.e., that males are more frequently injured at work than females. However, we found no evidence that lower-income, Hispanic youth were at greater injury risk than middle schoolers with better financial standing. Further investigation is needed to examine the impact of school-year work on youth functioning and to develop interventions to reduce work-related injuries in this population. Parents and professionals should monitor the number of hours of weekly work of middle school children.