This article tests the tenability of a Unified Model of Task-specific Motivation (UMTM). The UMTM integrates task-specific components from several theories of motivation. Core of the model are four interacting but relatively independent types of valences. Affective and cognitive valences represent feelings while doing an activity and thoughts about the value of its consequences respectively; both affective and cognitive valences can be positive and negative, hence calling for approach and avoidance motivation respectively. The interaction between these four types of valences results in a valence appraisal that influences readiness for action. Task-specific antecedents, autonomy, feasibility, social relatedness and subjective norm, influence valences. 441 Primary school teachers provided judgments of all components of the model except social relatedness for three imaginary professional learning activities. The three activities were framed as a school board decided, a team decided and a personally decided learning activity. Structural equation modelling showed that for each activity a separate model was needed. How valences influenced readiness for action was specific to each activity. In the board and team decided activities, for instance, readiness for action appeared to be based predominantly on cognitive valences, while in the personally decided activity affective and cognitive valences showed a more balanced contribution. Regarding task-specific antecedents, however, the picture was less clear. Nevertheless, the UMTM proved to offer rich possibilities for the explanation of complex motivational phenomena and promises a significant reduction of the superabundance of theories that encumbers motivation research.