"Unlike scientific theories, evaluation theories are prescriptive: a set of actions and approaches that should be followed when conducting an evaluation. While evaluation theorists have offered a variety of writings describing their theories and approaches, few have offered a specific outline of what the theory looks like i n practice. Thus, Alkin and Christie formulated a book to aid evaluators in how to apply theories in evaluations. This book culminates in a series of prototypes that outline each theory’s goals, appropriate contexts, prescriptions, and observable actions in application. Purpose: In order to aid evaluators in applying theories, this article seeks to provide a basis for comparison that can be used to help evaluators select which theory would be most appropriate in their practice. Setting: This comparison can be applied in any setting where evaluations fit the context prescribed by each of the theories. Findings: In order for theories to influence practice effectively, theories must be displayed in a way that allows for easy comparison. This comparison of three theory prototypes demonstrates that prototype can be an effective way for selecting a prescriptive theory when conducting an evaluation." (Summary)