Background <p>Nomothetic, group differential, and idiographic approaches are all needed to fully understand youth development. However, most research on youth character development has traditionally relied on either the nomothetic approach to study whole sample changes or the differential approach to study changes in predefined groups (e.g., involving gender or age).</p> Objective <p>In this study, we used data from the Thanda Study of Character and Health to assess nomothetic, differential, and idiographic development of character attributes (generosity, curiosity) among South African youth.</p> Methods <p>We measured character attributes using a traditional longitudinal design and an intensive longitudinal design (ILD). The traditional longitudinal design involved 222 youth (50% female; <i>M</i>_<i>age</i> = 9.82, <i>SD</i>_<i>age</i> = 1.39), and their scores of character attributes for three assessments separated by about half a year. A subset of 35 youth from this sample (48% female, <i>M</i>_<i>age</i> = 11.6, <i>SD</i>_<i>age</i> = 0.62) participated in the ILD, completing a survey of character attributes across 16 weekly assessments. Using Growth Mixture Modeling and person-specific pathways plots, we examined group-based heterogeneity and specificity in youth character development.</p> Results <p>Results from both designs confirmed that there is group-based heterogeneity in character development. Findings from the ILD additionally pointed to the specificity of character development and the fact that person-specific trajectories of the character attributes cannot be captured by the estimated mean trajectories of groups.</p> Conclusions <p>These findings underscore the importance of identifying both group-based and idiographic trajectories rather than relying solely on nomothetic or differential approaches on predefined groups when studying character development.</p>