<p>The article focuses on the role of motivational factors in the successful completion and satisfaction with postgraduate programs. PhD students (N=155, M=26,8, SD=4,2, 63% women) participated in the study. The theoretical framework is based on self-determination theory, which provides an understanding of the sources of autonomous and controlled motivation for research activity. A battery of questionnaires was used to assess autonomous and controlled motivation for postgraduate programs (the Universal Perceived Locus of Causality scales, UPLOC, and the Doctorate-related Need Satisfaction Scale, D-N2S), publication activity, intentions to complete the postgraduate program, and satisfaction with it. The results of the study demonstrated that autonomy need satisfaction was a predictor of autonomous motivation and satisfaction with the postgraduate program, whereas competence and relatedness needs satisfaction were predictors of intentions to complete the postgraduate program. Path models also showed that autonomy need satisfaction is a predictor of low levels of controlled motivation, which in turn is a negative predictor of intentions to complete the postgraduate program and satisfaction with it. It is concluded that it is important to study and monitor motivational factors, considering their predictive power in relation to PhD students' performance. Recommendations are offered to supervisors and faculty to support PhD students' basic psychological needs for autonomy, competence, and relatedness to foster their voluntary engagement and success in the research process.</p>