In this paper, we have explored how students in a cross-disciplinary course on engineering and social justice approached the idea of using social justice as a "lens" for looking at engineering. We have used an adapted phenomenographic approach [Marton, F., and Booth, S., 1997. "Learning and awareness". Mahwah: Lawrence Erlbaum], together with Meyer and Land's [Meyer, J.H.F., and Land, R., 2003. Threshold concepts and troublesome knowledge: linkages to ways of thinking and practising within the disciplines. "ETL Project Occasional Report 4" [online]. Available from: http://www.tla.ed.ac.uk/etl/docs/ETLreport4.pdf [Accessed 1 January 2009]] threshold concept framework, to study the variation present among the students in the class as they attempt to pass through the threshold of this lens. Data were collected through semi-structured interviews with students. We examine the liminal space that students hover in for several weeks, not knowing whether or if they will eventually pass through the portal into new territories. We found nine conceptions of increasing complexity present among the students in the class. We suggest that the students' collective experiences illustrate potential journeys along a spectrum of liminality and through the threshold. We conclude with some implications for what can be done to facilitate the students' transition through the threshold, thereby contributing to the development of this aspect of engineering education. (Contains 2 figures.)