Usability is one of the most important aspects of software. A multitude of methods and techniques intended to support the development of usable systems has been provided, but the impact on industrial software development has been limited. One of the reasons for this limited success is the gap between traditional academic theory generation and commercial practice. Another reason is the gap between usability engineering and established requirements engineering practice. This thesis is based on empirical research and puts a usability focus on three important aspects of requirements engineering: elicitation, specification and release planning. There are two main themes of investigation. The first is concerned with the development and introduction of a usability-oriented method for elicitation and specification of requirements, with an explicit focus on utilizing the skills of technical communicators. This longitudinal, qualitative study, performed in an industrial setting in the first half of the nineties, provides ample evidence in favor of a closer collaboration between technical communicators and system developers. It also provides support for the benefits of a task-oriented approach to requirements elicitation. The results are also reflected upon in a retrospective paper, and the experiences point in the direction of an increased focus on the specification part, in order to bridge the gap between usability engineering and established requirements management practice. The second represents a usability-oriented approach to understanding and supporting release planning in software product development. Release planning is an increasingly important part of requirements engineering, and it is complicated by intricate dependencies between requirements. A survey performed at five different companies gave an understanding of the nature and frequency of these interdependencies. This knowledge was then turned into the design and implementation of a support tool, with the purpose of provoking a deeper understanding of the release planning task. This was done through a series of cooperative evaluation sessions with release planning experts. The results indicate that, although the tool was considered useful by the experts, the initial understanding of the task was overly simplistic. As a result, a number of design implications are proposed. / On the day of the public defence the status of article VI was: Submitted.