This paper examines differences between the decision-making of marginal and nonmarginal students about participation in higher education (HE). We distinguish between two kinds of marginality: being "borderline" on account of prior achievements in school and being "unsure" after taking prior achievement into account. We identify a significant minority of students in their final year of schooling who are unsure about participation in higher education even though they have prior school achievements typical of entrants to HE. Being "unsure" is found to be unrelated to socioeconomic background, but it is associated with significantly different attitudes towards the potential benefits and risks of participation, different levels of knowledge about financial support that is available and different approaches to information search about participation in HE.