In this study, the effects of proactive personality traits on the proactive work behavior and work engagement are examined. The study aims to examine whether proactive personality structure of employees working for Development Agencies in Turkey has any effect on proactive work behavior, work engagement of people. In line with this aim, data from 151 people working in Development Agencies were collected by the questionnaire method and these data were analyzed by hierarchical regression method in order to determine the direct and regulatory effects of the variables included in the model. As result, it is reviled that proactive personality and proactive work behavior has a positive relationship, moreover, work engagement has a mediating effect on this relationship.