A recent multiple-stage model posits that the individual-difference factors influencing performance vary depending on skill acquisition stage (P. L. Ackerman, 1989, 1990). In the current study, the authors examine the effect of ability in early skill acquisition and extend earlier research by examining the roles of self-efficacy and task familiarity. Furthermore, learning-curve modeling with multilevel models is used to alleviate prior analytical problems. Subjects (N = 115) performed an air traffic control simulation task. Nonlinear learning-curve parameters were estimated for each subject using a negative exponential model (see D. R. Rogosa & J. B. Willett, 1985). Cognitive ability, self-efficacy, and task familiarity were then used to predict learning-curve parameters: learning-rate constant and asymptotic performance. Results revealed that ability, self-efficacy, and familiarity predicted the learning-rate constant, whereas self-efficacy predicted asymptotic performance.