Product platforms have become a principal fundament and a prerequisite for profitable product development in almost every industry today. Since platforms have a desirable potential to reduce development and production costs, there is an extensive bulk of knowledge describing underlying platform principles and challenges. But the vast majority of the identified challenges are based on single firms and brand contexts, which imply that previous findings might not be applicable when platform development involves several brands, here called multibranded platforms. In the present article it is therefore suggested that there is lack of knowledge describing managerial challenges of multibranded platform development. To be able to capture such a strategy that holds certain complexity and unknown dimension, an explorative and longitudinal field study is supposed to achieve the finest insights into a yet incompletely documented phenomenon. Because of the field-study approach, findings from the study are theoretically validated in relation to existing knowledge from other contributions. To start developing a multibranded product platform development framework, the present study identifies three distinctively different strategic forces that must be handled in such multibranded platform development: (1) the creation of a common architecture; (2) accomplishing product differentiation within an expanded and multibranded product scope; and (3) corporate responsibility in the transition from single-branded to multibranded platform development. Three dimensions of managerial challenges are identified. The first is technology management challenges, which deal with commonalization in terms of the development of common multibranded architectures. The major challenge to achieve architectural commonalization is that no individuals from any brand have the proper multibranded architectural knowledge. Instead, multibranded architectures must evolve from the beginning and be founded on a new and expanded brand scope. Architectural commonalization also includes elements of unlearning since previous experiences have little relevance. The second challenge is brand management challenges and deals with brand differentiation in terms of portfolio management. Differentiation is an effect of increased diversification that particularly challenges brands of opposite generic competitive strategies. The third challenge dimension is called corporate management challenges and deals with the combination of the two others. From a corporate management perspective, it seems important to provide new organizational structures that support and combine interests of technology and brand management. Finally, multibranded platform development is a corporate strategy that affects business units and functional units thoroughly.