Abstract
Longitudinal research is a unique research method that allows studying changes in individuals over time and how these changes vary within and across individuals. The goal of this entry is to give an overview about longitudinal research. The first part defines longitudinal research and discusses different perspectives of longitudinal change. The second part presents longitudinal research designs as a function of the temporal design. Traditional longitudinal research designs focus on developmental change, whereas intensive longitudinal research designs aim to capture short‐term dynamic processes. The third part discusses the diary method and ambulatory assessment as two examples of intensive longitudinal research methods that allow studying processes in daily life. The final part presents the measurement‐burst design that combines more traditional and intensive longitudinal research designs in an integrative way.