That people need to be motivated in order to achieve their goals is fairly acknowledged when it comes to most aspects of life. So is the notion that motivation that strives from within usually produces the best results. This has certainly been proven to be the case in for example, psychical education, but does it also apply to second language learning? This systematic literature review was done to explore what factors motivate students when learning a second language and could the Self-determination theory help put the findings in perspective. The research questions that were asked were 1: What are the motivational factors that past research studies have identified for L2 learning? And 2: Where on the Selfdetermination theory continuum are the students feeling the most motivated when it comes to L2 learning? The results show that intrinsic motivation was once again a strong predictor of engagement and learning also when it came to learning a second language. Important factors to reach intrinsic motivation were found to be autonomy, classroom climate and teachers.