This study examines the mechanistic model, the organismic model, and the contextual model as the existing paradigms for developmental changes. Several new perspectives have emerged in the physical and natural sciences and are collectively referred to as the complexity sciences As a new paradigm, The complexity science is call into question many of the basic principles and tenets upon which traditional scientific inquiry is based. Centering the chaos, nonlinearand self-organization, the complexity science is dicussed. Also the relationships of the complexity science with psychology and developmental psychology and study method of the complexity science for developmental psychology are examined. As a result, it is dicussed that the complexity science gives useful information for normal and abnormal development.