The emergence of a new theoretical framework for research in human development is discussed. The theoretical perspective is contrasted with the classical laboratory experiment, which produces ecologically invalid research because of the restrictions of the artificial laboratory environment. The emerging framework enhances ecological validity by incorporating four sets of properties: (1) reciprocality, which refers to the two-way nature of the model, so that the child is viewed as a stimulus and a socializing agent as well as a reactive being; (2) role specification, characterized by role delineation for each participant in the research and the systematic examination of these roles as independent variables; (3) N-person versus two-person systems, which refers to the extension of the number of participants studied (study of mother-child, father-child, mother-father interactions as opposed to mother-child interaction only); and (4) second-order effects, the study of the effects of a third person or external agents (e.g., equipment designed for infant stimulation or, at an older age level, television) on human interaction. It is argued that most environmental variance on human behavior derives from second-order impact of societal institutions, and therefore an examination of secondary effects is valuable for scientific analysis and the enhancement of human development. [Not available in hard copy due to marginal legibility of original document.] (DP)