A review is presented of studies which examine the psychological predictors of successful adult performance, or life skill success. Scholastic achievement is generally regarded as an ineffective predictor of successful life performance. It is suggested that factors such as ego maturity and personal competence (developmental psychological characteristics) are responsible for differentiating between effective and ineffective performance. An accepted theory states that levels of psychological maturity and levels of conceptual development determine the quality of adult functioning. A multiple series of studies also documents that the effective versus ineffective functioning of adults in general and of adults in teaching is determined by the maturity-developmental level of the adult. Attempts are being made to create developmentally oriented education programs for preservice and inservice teachers. Appended to this paper is a discussion of the state of the art for a possible developmental approach to inservice teacher education. (JD)