Decision-making is one of the most important elements in the administration of any organization. University libraries are, of course, organizations. Inside these organizations the managers make a variety of decisions that will have a significant impact on the success of those libraries. Libraries' managers utilize different methods in processing their decisions. Many factors play roles in the success of libraries' managers. The manager's managerial decision style is one factor that contributes to the success of the manager and therefore to the success of their organization; and yet, there is a dearth of research about decision styles used in library administration and how they influence the decision-making process. The main purpose of this study was to explore the managerial decision styles of the managers (directors, associate directors, assistant directors, and the heads of departments) of Florida's state university libraries. A second purpose was to determine the relation between the variety of managers' decision styles and the following seven variables: gender, age, ethnicity, educational level, educational major, administrative experience, and current position. The results of this study will provide baseline information to improve our understanding of library managers and management. This study was grounded in the Decision Style Model developed by Alan Rowe and Richard O. Mason (1987). A survey questionnaire was employed in this study. The questionnaire included two parts: 1. "The Decision Style Inventory" (DSI) developed by Row and Mason (1987). This inventory was applied to measure the decision styles of the managers of Florida's state university main libraries. 2. The second part of the questionnaire consisted of questions designed to obtain descriptive data such as gender, age, ethnicity, educational level, educational major, current position, and administrative experience. According to the Decision Style Model, it was found that the predominant decision style for the majority of Florida's state university main libraries' managers was the behavioral decision style, followed by the conceptual decision style. The directive decision style was the style used least often by most of these managers. As for the decision style patterns, the findings inform us that the majority of Florida's state university main libraries' managers think using the right side of the brain rather than the left side. It was also found that there was no relationship was found between Florida's state university libraries' managers and their gender, age, or highest academic degree. On the other hand, the findings of this study indicated that years of administrative experience, ethnicity, position, and educational major of these managers were indeed related to the decision style or styles used by these managers. To date there has been no research conducted on profiling the decision styles of Florida's state university libraries' managers and the process of how they think in order to reach their decisions. Given this, the results of this study provided baseline information to improve our understanding of library managers and management in general and in particular, understanding of library managers and management in Florida's state university libraries.