In the current changing and competitive world, organizations spend a large part of their energy to their employees, that their performance is the main factor of the success of organizations. Several factors affect the staff’s task performance, including the Islamic work ethic, positive feelings toward work and work engagement. The goal of this study is to investigate the effect of these factors using descriptive-causal methods on the task performance. Considering the important role of universities to educate the human resources, public universities were designated as the statistical community. Then based on the relationships between variables, assumptions and conceptual model were presented. Next, using data from a population of 280 people and by the techniques of factor analysis and principal component analysis, the variables of the model, presented in the research, conceptualized, and then hypotheses tested by using multiple regression. Results showed that task performance both directly and indirectly influenced by the Islamic work ethic (/45), Positive effect to work (/50) and job engagement (/19).