Research has long suggested that higher education leads to liberalisation in students' sociopolitical orientations (e.g., Feldman & Newcomb, 1969; Newcomb, 1943/1957; Pascarella & Terenzini, 1991). Differences in level of liberalisation depending on academic discipline have also been found (e.g., Baer & Lambert, 1982; 1990; Guimond & Palmer, 1990; 1996). Two hypotheses have been proposed to explain these differences: self-selection, where people choose disciplines whose views most closely match their own; and socialisation, where people's belief systems change to match their discipline's. Two key mechanisms are thought to drive socialisation: normative (people's attitudes change to match those around them) and informational influences (provision of specific knowledge creates attitude change). This paper reviews the major evidence of liberalisation of students' orientations, as well as evidence for the self-selection and socialisation explanations, and for normative and informational influence. It concludes with suggestions as to how future researchers can investigate whether change occurs and the processes by which this may be occurring. (Contains 4 notes.)