A plethora of theoretical perspectives on the phenomenon of IT outside of the IT department exists. One recent perspective is lightweight IT as introduced by Bygstad [1]. It is interesting as it takes a positive view on this phenomenon and contrasts lightweight from heavyweight IT. To reflect on the current understanding of lightweight IT this paper presents a systematic literature review. Publications are assessed regarding their contribution to the conceptualization of the interplay of heavyweight and lightweight IT and the benefits and corresponding risks of lightweight IT in practice. Based on these insights, drivers, benefits, and risks of lightweight IT are derived. This allows a comparison with the parallel research streams of IT Consumerization and Shadow IT as the two other dominant perspectives on the phenomenon of IT outside of the IT department. The comparison shows significant overlap, but also conceptual differences. As a result, six questions for further research are derived.