The purpose of the present research was to examine the influence of communication goals and physical demands on the expression of communicative (e.g., facial grimaces) and protective (e.g., guarding) pain behaviors. Participants with musculoskeletal conditions (N=50) were asked to lift a series of weights under two communication goal conditions. In one condition, participants were asked to estimate the weight of the object they lifted. In a second condition, participants were asked to rate their pain while lifting the same objects. The display of communicative pain behaviors varied as a function of the communication goal manipulation; participants displayed more communicative pain behavior when asked to rate their pain while lifting objects than when they estimated the weight of the object. Protective pain behaviors varied with the physical demands of the task, but not as a function of the communication goals manipulation. Pain ratings and self-reported disability were significantly correlated with protective pain behaviors but not with communicative pain behaviors. The results of this study support the functional distinctiveness of different forms of pain behavior. Findings are discussed in terms of evolutionary and learning theory models of pain behavior. Clinical implications of the findings are addressed.