Introduction: Although metacognition is considered to be a key component of academic success, few studies have explored the interactions between the development of metacognitive processes beyond adolescence and variables such as sex and education. In particular, there is a gap in the literature about how these variables determine differences in the metacognitive processes that are self-reported by university students. The present study aimed to ascertain how metacognitive processes related to planning of writing in higher education interact with sex and education (i.e., learning domain, high school diploma track). Our specific research questions was: Is the sex of university students a predictor for the levels of metacognition related to planning of writing? Additionally, we examined to what extent educational background and learning domain factors determine differences in the metacognitive processes self-reported by university students. Method: A questionnaire that investigated three specific metacognitive dimensions was administered to 1051 students enrolled in different learning domains (Human and Social sciences, Language and Literature, Law and Economy and Sciences). Factor analysis (exploratory and confirmatory) showed three components measured by this instrument: conditional metacognitive knowledge (six items), covert or personal self-regulation (four items) and environmental self-regulation (five items). Participants were asked to identify the extent (using a Likert-like scale) to which a given strategy or type of knowledge reflected their planning of writing processes. This questionnaire also elicited information about respondents' sex, level of study, high-school diploma track and learning domain. Results: The results showed that 1) female students self-reported the highest level of metacognition in planning of writing, particularly related to two metacognitive processes: conditional metacognitive knowledge and environmental self-regulation. Additionally, regression analyses showed that sex was a predictor for student's self-reported conditional metacognitive knowledge. 2) The technical and vocational French high school tracks induced statistically significant differences in the metacognitive processes. There were negative predictors for certain latter processes. There were also statistically significant differences in the self-reported scores of metacognition in the function of the learning domain. Discussion and Conclusion: The first result is consistent with findings about the superiority of women in the communication domain, while the second finding highlights the contribution of skills acquired at secondary school towards learning at university.