This study was to investigate the validity of the definition of Learning Disabilities(LD) concept based on the research data thus far obtaind, and present necessity of reconceptualization. To review the evolution of LD definition, it has been the 'problem' almost from the outset and is now. That is, LD field has been plagued by definitional problems that have seriously undermined progress in the field. The primary conclusion to be drawn about LD definitions is that the more they change the more they stay the same. The history of the LD field reveals that the seminal work of Strauss and Werner evolved into the present-day LD field through the efforts of their colleagues and students who incorporated the paradigmatic assumptions of Strauss and Werner into basic conceptualizations about the nature and definition of LD. The Strauss and Werner 'paradigm' includes (in varying degrees) the following postulates: (a) LD fits a medical model(implying something wrong with the child), (b) LD is associated with (or caused by) neurological dysfunction, (c) LD academic problems are related to process disturbance, most notably in perceptual-motor functioning, (d) LD is associated with academic failure as defined by discrepancy notions, and (e) LD cannot be due primarily to other handicapping conditions. Evaluation of the primary definitional components(postulates) of LD derived from the 'paradigm' developed Strauss and Werner finds that each is problematic and cannot be accepted unequivocally. Subsequent research has failed to demonstrate the manifest validity of the paradigmatic assumption found in LD definitions. Consequently, the Strauss and Werner 'paradigm' cannot be viewed as a universial framework for scientific development in LD. THe problematic nature of the LD definitional components suggests that they represent anomalis. But LD field has not experienced a paradigm shift that would explain the anomalies and provide new theoretical perspectives. Therefore, a necessary step in resolving the problem of definition is to cease efforts at modifying available definitions. The LD field must be understood as really being in a preparadigmatic period where all conceptualizations are approprite and justified for defining LD. Through constructive, cumulative, and cooperative endeavors, LD can then be validly defined.