Increasing customisation, together with a focus on assemblers’ value added time, inflates the number of component variants required in assembly, and drives implementation of kitting processes. Practice indicates that current kitting process designs exhibit quality problems, but research is scarce concerning which problems arise and why. Therefore, this paper provides a decomposition of quality in kitting processes by establishing a framework consisting of types, causes and determinants of quality problems in kitting processes. Through a multiple case study, several underlying mechanisms of quality problems and why they arise were revealed, thereby extending the current frame of knowledge.