Identifying and systematizing software practitioners’ perceptions of a problem in development projects is an important first step in searching for a solution to the problem. Moreover, different tiers in an organization might have diverging perceptions of the problem. Disregarding such diverging perceptions might lead to a situation where one loses commitment from some or all of the involved parties.In this study we investigated practitioners’ perceptions about challenges in integration projects at a major software vendor, Company X. When integrating their in-house products, Company X often faces major challenges, and representatives of the company observe that substantial resources are spent on the integrations. In order to investigate these challenges, the perceptions of practitioners working on the integrations were elicited using the semistructured interview technique Repertory Grid. A total of nine interviews from three organizational tiers were conducted. The three tiers were developers, QA managers and project managers. The interviews were thoroughly analyzed, both on an individual and on an aggregated basis, to explore what the actual challenges were, as well as possible relations between the challenges, such as the challenges’ relative importance. We found that perceptions differ substantially between the tiers. While the developers’ main concerns are challenges related to technology and knowledge, the QA managers perceive challenges related to human resources and responsibilities for the integration tasks as most important. The product managers, on the other hand, are most concerned about human and organizational issues. We also discovered internal variations within the tiers. The developers seem to be most united in their perceptions, while the QA managers and product managers have a higher level of agreement across the tiers than internally.A connection between the interviewee’s education and experience, and their perceptions was also discovered in addition to minor terminological differences.The study also gave rise to an ontology for integration challenges based on a categorization of the challenges elicited from the practitioners. The ontology has provided the company with a structure of the challenges with three levels of abstraction, and might also be an initial step for a general ontology for challenges in integrations.