The purpose of this dissertation is to explore how the economic return of a software investment can be assessed and managed. This topic has been studied in research and has been a concern for firms making software investments. In order to study this we need a model of the underlying factors affecting the economic return. Assessing and managing the return of a software investment is been argued to be difficult due to specific economic characteristics of a software investment, i.e. high degree of intangible consequences and uncertainty about the total investment cost. Given these characteristics it is has been concluded that it is difficult to derive a return function. In this dissertation we question this conclusion and propose a comprehensive model to assess and manage the intangibles and the underlying uncertainty. The model is deduced from general assumptions of the economic behavior of the firm. To develop the model we analyze the relevance of intangibles in relation to the economic purpose of making a software investment. Based on this a new way of deriving a cash flow function for a software investments is defined. Further it is analyzed how the underlying uncertainty of a software investment can be managed. The analysis uses a quantitative approach and methods from financial economics. It includes how the application of a real option and portfolio approach can reduce the uncertainty in a software investment and the role of efficient software platforms. The relation between software platforms and the opportunity to create different types of real options for future development is inferred from empirical studies. The studies in this dissertation show how a managerial view on a software investment corresponds with the overall economic goal of the firm. They also show how a strategic value of a software investment can be created, assessed and managed.