Some researchers have questioned the use of dropout metrics to assess the quality of MOOCs. The main reason for this doubt is that participants register for online courses with different intentions. Therefore, it is proposed to use a learner-centred approach and to study the learner intention-fulfilment. Researchers studied the effect of result-oriented intention on MOOC completion. However, studies in traditional educational settings have shown that a more significant predictor of behavior is not result-oriented intention, but action-oriented intention. In our paper, we expand the study of the intention-to-behavior relation in MOOCs and identify the role of strong positive action-oriented intentions in MOOCs. As strong positive action-oriented intentions, we identified two types of intention: intention to watch all the video lectures and intention to complete all the tasks. The research database consists of trace data and survey data collected among participants of 5 MOOCs launched in the spring semester of 2017. Survey data recorded one result-oriented intention (to earn a certificate) and the two strong positive action-oriented intentions. The results showed, first, a significant relationship between strong positive action-oriented intentions and behavior in MOOCs. Secondly, we found that the intention to watch lectures and to complete tasks are conceptually different intentions: the intention to watch lectures does not play a significant role in course completion compared to the intention to complete all the tasks. Thirdly, we found that the strong positive action-oriented intention to complete all the tasks is a more powerful predictor of course completion than the result-oriented intention. These results can be used to adjust interventions that are embedded in the courses to increase their effectiveness.