Knowledge acquisition, the process of extracting information from human experts, is one of the challenges in building expert systems. Modern practitioners and researchers need more guidance than is provided by existing knowledge acquisition guidelines. However, there has been little empirical research upon which to base the needed guidelines. This paper surveys the available knowledge acquisition techniques and describes a knowledge acquisition experiment which contrasts three of these methods. A framework was developed to categorize the types of heuristic which can be elicited with different means of knowledge acquisition. This research represents the initial steps in a research program focused on the development of empirically evaluated, generalized guidelines for effecting .knowledge acquisition.