There is a growing acceptance of a holistic, interactionistic view in which the individual is seen as an organized whole, functioning and developing as a totality. This view emphasizes the importance of patterns of operating factors. Within this framework, a standard variable-oriented approach, focusing on the variable as the main theoretical and analytical unit, has limitations. A person-oriented approach would often be preferable, where the main theoretical and analytical unit is the specific pattern of operating factors. Such an approach is presented here, focusing on individual development and psychopathology. A brief theoretical and methodological overview is given and a classification approach is emphasized. Empirical examples concerning the longitudinal study of adjustment problems illustrate a number of issues believed to be important to development and psychopathology: problem gravitation, the significance of single variables and of patterns, the developmental study of syndromes (= typical patterns), and the detection of "white spots" in development.