Existing studies of supplier involvement in new product development have mainly focused on project-related short-term processes and success factors. This study validates and extends an existing exploratory framework, which comprises both long-term strategic processes and short-term operational processes that are related to supplier involvement. The empirical validation is based on a multiple-case study of supplier collaborations at a manufacturer in the copier and printer industry. The analysis of eight cases of supplier involvement reveals that the results of supplier–manufacturer collaborations and the associated issues and problems can best be explained by the patterns in the extent to which the manufacturer manages supplier involvement in the short term and the long term. The results of this study reveal that the initial framework is helpful in understanding why certain collaborations are not effectively managed yet conclude that the existing analytical distinction among four different management areas does not sufficiently reflect empirical reality. This leads to the reconceptualization and further detailing of the framework. Instead of four managerial areas, this study proposes to distinguish between the strategic management arena and the operational management arena. The strategic management arena contains processes that together provide long-term, strategic direction and operational support for project teams adopting supplier involvement. These processes also contribute to building up a supplier base that can meet current and future technology and capability needs. The operational management arena contains processes that are aimed at planning, managing, and evaluating the actual collaborations in a specific development project. The results of this study suggest that success of involving suppliers in product development is reflected by the firm's ability to capture both short- and long-term benefits. If companies spend most of their time on operational management in development projects, they will fail to use the leverage effect of planning and preparing such involvement through strategic management activities. Also, they will not be sufficiently able to capture possible long-term technology and learning benefits that may spin off from individual projects. Long-term collaboration benefits can only be captured if a company can build long-term relationships with key suppliers, with which it builds learning routines and ensures that the capability sets of both parties are aligned and remain useful for future joint projects.