Change and uncertainty are integral elements of any organization, yet they are not easy to face and they elicit a wide range of responses among organizational members. This study uses a rhetorical approach to examine the communications directed to employees in one type of organizational change---mergers and acquisitions;Based on a review of the mergers and acquisitions, management, organizational behavior, and rhetoric and professional communication literature, I identify four major rhetorical challenges that need to be addressed in the early communications in mergers and acquisitions: setting the stage for cultural change, addressing emotions, dealing with uncertainty, and building an identity and encouraging identification;I use early communications collected from two research sites (a seed company merged with a competitor and an accounting firm acquired by a public company) in examining how the rhetorical challenges were addressed in these situations. I use interview data to examine employee perceptions of the communications;I use fantasy theme analysis, a method of rhetorical criticism developed by communications scholar Ernest Bormann, to determine how the communications worked in achieving a common understanding of the merger or acquisition within the organizations. I identify a number of themes used in the communications to address the rhetorical challenges;I argue that fantasy theme analysis is a valuable method to use in analyzing professional communications; it provides a way of focusing on commonalities and differences in communications used in similar types of situations in different organizations. I argue that my analysis sheds new light on genre theory. Genres are generally thought of as recurring rhetorical responses to recurring rhetorical situations. I argue that fantasy theme analysis provides a way of identifying recurring responses (fantasy themes) to situations that recur in the organizational lifeworld as a whole, even though they may not recur frequently in any one organization. I introduce the notion of "thematic genres" to refer to these genres that can be identified through common fantasy themes. I also offer a heuristic based on my fantasy theme analysis that could be used by those preparing employee communications in mergers and acquisitions and other situations of major organizational change.