Context: At the core of choosing what features and level of quality to realize, and thus offer a market or customer, rests on the ability to take decisions. Decision-making is complicated by the diverse understanding of issues such as priority, consequence of realization, and interpretations of strategy as pertaining to the short-term and long-term development of software intensive products. The complexity is further compounded by the amount of decision support material that has to be taken into account, and the sheer volume of possible alternatives that have to be triaged and prioritized; thousands or even tens of thousands of requirements can be the reality facing a company. There is a need to develop the functionality that is strategically most significant, while satisfying customers and being competitive, time efficient, cost effective, and risk minimizing. In order to achieve a balance between these factors, all the stakeholders, within an organization, need to agree on the strategic aspects and value considerations to be considered, and their corresponding relative importance. Objective: The objective of this thesis is to provide enhanced decision support for product managers faced with decision-making challenges. This involves, but is not limited to, enhancing the alignment between the product and portfolio management with respect to product strategies, and enabling the use of value as a basis for product management and development related decisions. Method: A number of empirical studies, set in industry, have been performed. The research methods used span from systematic mapping, and systematic reviews to case studies, all aligned to identify possibilities for improvement, devise solutions, and incrementally evaluate said solutions. Close collaboration with industry partners was at the core of the research presented in this thesis. Result: The MASS method presented in this thesis can be used to evaluate strategic alignment and identify possible root causes for misalignment. To strengthen strategic alignment, the Software Value Map and corresponding decision support material, proposed in the thesis, can be used by product managers for making effective and efficient strategic decisions in relation to portfolios, products and process improvement, following a systematic and aligned process. Conclusions: The area of software product management, in the context of market-driven software intensive product development, is a field with unique challenges. The specifics of the solutions are based on industry case studies performed to gauge state-of-the-art, as well as identify the main challenges. The decision support developed takes the form of maps and frameworks that support software product management on product and portfolio level decisions, strategic alignment, value-based requirements selection, and value-based process improvement.