Imagined interactions are mental representations of conversations with significant others. One function they may serve is as a rehearsal for an anticipated encounter. The process by which this rehearsal occurs is investigated using Dillard’s (1990) Goals-Plans-Action model and Berger’s (1997) Planning Theory of Communication. A causal model is proposed for the relationships between domain knowledge, use of retroactive imagined interactions, specificity, and discrepancy of the proactive imagined interaction. This model is tested using survey data (N = 210), and additional data were collected assessing characteristics of the anticipated conversations. Results and additional analyses suggest that rehearsal occurs in many different contexts, that domain knowledge moderates the relationship between retroactivity and specificity, that specificity and valence of imagined interactions influence discrepancy, and that valence and discrepancy influence the achievement of social goals. These findings are discussed in reference to the planning and imagined interactions literatures.