The concept of development is currently under revision in education and psychology. In this essay, Eugene Matusov, Renee DePalma, and Stephanie Drye examine a traditional notion of development and provide an alternative sociocultural view. As educators working within a sociocultural approach to learning, development, and education, the authors see psychological phenomena as rooted in participation in sociocultural activities, practices, and communities. They critique how the traditional notion of development essentializes this process, assuming development to be independent of the observer. Using a case where a child of color develops a "sitting disability" within the institutional context of schooling, they illustrate the need for introducing a sociocultural notion of development, arguing that development is a social construction emerging in communities of practice and that it is necessary to consider the role of the observer in both defining and guiding this process in a professional discourse of cases.