Abstract Employing an extended case method ethnography (Burawoy 1998), the researcher joined five new members forming a spiritualist's group under the leadership of an experienced advocate. Over a period of eighteen months, the researcher attended all the group's activities and events. Data were collected to reflexively interrogate the process theory of conversion proposed by Lewis Rambo (1993). The data revealed conversion to be a multifaceted and dynamic process of cognitive change, mediated by structural, and contextual forces. The results provide a reconceptualization of Rambo's theory, presenting a theoretical expansion of the model emphasizing its mechanisms of action. The paper details the composition of the “Interaction-Commitment” mechanism, operationalized within four submechanisms emanating from Rambo's roles, rituals, rhetoric, and relationships. This longitudinal study shows that most of the hard work toward conversion occurs before any formal interaction with a conversion advocate. Conversion operates most effectively under conditions of cognitive economy wherein the belief path follows a path of least cognitive expenditure.