The present study attempted to answer two general questions: (1) what is the relation between expected and actual reactions to a spider in individuals afraid of spiders? and (2) are inaccurate expectancies updated on the basis of experience? Behavioral and cognitive-behavioral learning models of fear, treatment protocols developed in relation to these, and recent findings from our laboratory necessitated answers to two additional questions: (3) does the expectation accuracy of individuals who meet DSM-IV criteria for diagnosis with a specific phobia differ from that of individuals who are fearful but do not meet criteria? and (4) does expectation accuracy vary as a function of context? Two final questions were obvious: (5) do the actual reactions of individuals who meet criteria for diagnosis differ predictably from those of fearful individuals? and (6) do reactions vary contextually? Student participants reported and tested a series of trial-specific expectancies about their reactions to a live, mechanical, or virtual tarantula over seven trials. Participants then completed three final trials in the presence of a live tarantula. Participants poorly anticipated the quality and intensity of their initial reactions, but expectation accuracy increased quickly. No clear tendencies for over- or under-prediction emerged. Participants updated expectancies in relation to prior trial expectation accuracy, either increasing or decreasing their predicted reactions relative to the original expectancy. Participants who met criteria for diagnosis with a specific phobia consistently anticipated and reported more intense reactions than did those who were fearful, but diagnostic status was not predictive of expectation accuracy. Participants in the live and virtual spider groups reported similar levels of fear that were greater than those in the mechanical spider group. Participants in the virtual spider group more readily reduced the distance maintained between themselves and the spider stimulus than did those in the live or mechanical spider groups. Expectation accuracy did not vary contextually. Results are discussed in light of the theoretical models presented, with findings lending greater support to behavioral models of fear learning relative to cognitive models that postulate a substantial role for conscious processing and appraisal in specific fear. Practical recommendations are made to researchers and clinicians based on present findings.