An investigation of the development of adolescents' motivation and achievement in school demonstrates how psychology and neuroscience can profit from each other in an empirical and therefore epistemological way through method triangulation. Based on a method triangulative technique that directly links quantitative, experimental, and qualitative data (Treumann, 2005), an interdisciplinary longitudinal (two measure points) study was designed to bridge the gap between neuroscience and psychology in the field of brain development and motivation in adolescence. By using this triangulative technique, the authors minimize the weaknesses of each method and maximize their strengths by combining disparate but complementary approaches. Future implications and challenges of method triangulation in the field of psychology research are discussed.Keywords: method triangulation, motivation, brain development, adolescence, neuroscience Many research topics straddle two or more disciplines. In the past, the scientific community tended to support the independence of each discipline, illustrated by the increasing number of discipline-specific methods and foci. Today, however, there is an international trend in science towards an interdisciplinary approach. The advent of neuroscience subdisciplines in the field of learning and motivation, such as neuroeducation, social neuroscience, and cultural neurosciences, have enabled novel discoveries to concern the universality and diversity in the dynamic interplay of genes, brain, and behavior. Although the formal study of these subdisciplines has only recently emerged in the past decade, the question of how environment (culture) and biology mutually constitute each other has long been a source of philosophical and scientific curiosity, dating as far back as the 7th century (Chiao, 2010). However, the theoretical and empirical tools necessary to make progress in addressing these outstanding questions have only recently become available. One methodological technique that provides opportunity to cross disciplinary boundaries in an empirical way is method triangulation.