Objective: To assess lateral differences between ossification events and stages of bone development in the hands and wrists utilizing Fishman's skeletal maturation indicators (SMIs). Materials and Methods: The skeletal ages of 125 subjects, aged 8 to 20 years, were determined with left and right hand-wrist radiographs using Fishman's SMI assessment. Each subject was also given the Edinburgh Handedness Questionnaire to assess handedness. The skeletal ages of both hand-wrist radiographs were analyzed against each other, handedness, chronologic age, and gender. Results: There were no significant differences overall in right and left SMI scores (P 5 .70); 79% of all patients showed no difference in right and left SMI scores, regardless of handedness, gender, or age. However, when patients were categorized based on clinical levels of SMI score for the right hand-wrist, there was a significant difference (P 5 .01) between the SMI 1-3 group and the SMI 11 group. Subjects in the SMI 1-3 group were more likely to show a left . right SMI score, while subjects in the SMI 11 group were likely to show a right . left SMI score. Conclusion: Although no significant overall lateral differences in SMI scores were noted, it may be advisable to obtain a left hand-wrist radiograph and/or additional diagnostic information to estimate completion of growth in young surgical patients. (Angle Orthod. 2015;85:408-412.)