The research reported here addresses the weak theorisation of the psychodramatic concept of ‘warm-up’. Warm-up is a socially instrumental concept used as a measure of the preparedness of a group or individuals for action and for an individual’s state of readiness in a given context. In the milieu of psychodrama the capacity for perceiving these elements is considered to be extremely important and the dearth of adequate theorisation highlighted an important lack, creating an absolute requirement for this research for both practitioners and researchers alike. There followed a critical analysis of the historical and current uses of the concept of warm-up, which concluded that warm-up was described in the psychodrama literature as a single heuristic that actually covers four different concepts, which, although evident in its use, have not been explicitly recognised. These four concepts are: The group warm-up process, the group warmup state, the individual warm-up process and the individual warm-up state, which is the focus of this research. The definition produced by the critical analysis was succinct for that purpose, but a comprehensive elaboration was called for. Initially, the succinct version was deconstructed into its fundamental forms, followed by a reconstruction and comprehensive conceptualisation of the individual warm-up state. Research indicated a lack of clearly articulated, consistent, and agreed criteria that might be used by researchers for determining the adequacy of a given concept for a given task. Such a framework was essential for determining the conceptual integrity of any new conceptualisation. Thus, a framework of criteria was developed for this purpose and illustratively applied to the evaluation of the general concept of warm-up in psychodrama. The framework comprises eight criteria in three categories: the intrinsic qualities of a concept (the criteria of clarity, comprehensiveness, parsimony, and resonance), the contextualisation of a concept (differentiation and connectedness), and its application (epistemic utility and practical utility). Using the framework to evaluate the concept of warm-up in the context of its use in psychodrama suggested the framework’s potential to make significant differentiations amongst concepts. This framework may contribute, significantly, to evaluating other concepts in other contexts. The framework indicated very clearly the inadequacy of the concept as it was. In order to test the concept with those who use it a methodology for field-testing concepts was developed and trialled in a study involving respondents critiquing the newly developed conceptualisation of the individual warm-up state. Online software to communicate with 485 selected experienced psychodrama and group therapy participants inviting a critical text-based evaluative response to the new conceptualisation with a response rate of 24.1%. Responses with substantive critical comment were examined and clustered according to the criterial framework. An overview of the results of the field-testing showing significant support for the new conceptualisation and critical input that led to for improvement. The criterial framework was used as a means of separating out the content of the responses and working through the field-test data. A detailed consideration of the field-testing data led to a clarification of 20 essential questions arising from the data. Each question was responded to evaluatively in its own section with explanations and justifications leading to modifications that were incorporated into the final reconceptualised definitions. In order to do the research of this thesis three additional outputs were developed: a criterion-based framework for evaluating the adequacy of an existing or retheorised concept, a methodology for field-testing such reconceptualisations, and a structured process for incorporating the field-test results in a final reconceptualisation. Taken together, these three outputs may be seen as forming a credible and complete reconceptualisation methodology. Uses of each of these outputs is considered and they each individually and collectively may have many potential knowledge-enhancing possibilities. In addition the general concept of warm-up has been determined to be four principal concepts, and one of those, the individual warm-up state, as the concept that was the focus of this research, has been defined comprehensively and with precision. The recognition and validation of the new conceptualisation creates the necessary conditions for the concept to be used for research particularly into: the individual warm-up state; the relationship implications; and psychodrama. Of significant interest is the possibility that the concept may be used for making sense of the notion of context in psychological and other research.