Whilst numerous studies have retrospectively reported the impact of negative user emotions, motivational problems or value clashes during software developments, few Requirements Engineering (RE) studies have considered the elicitation of users' values, motivations or emotions (VM&Es) and there is little advice for practising analysts as to how to deal with these factors.This thesis explores the impact of users' VM&Es within RE work. The starting point was a review of the current state of analyst practice. A literature survey considered the RE guidance available to analysts on the elicitation and understanding of 'soft issues' such as VM&Es. In parallel, a series of interviews with 12 industry analysts sought their views on the relevance of users' VM&Es, the impact on requirements work, and approaches to identifying such information. This study identified behaviours adopted by experienced analysts that would be useful to promote to novice analysts, and documented the analysts' own requirements for a method to support them in eliciting VM&Es. These findings informed the design of the Value Based Requirements Engineering (VBRE) method and website (www.vbre.org.uk), intended to support requirements analysts in identifying and considering the impact of such 'soft factors'. Research into RE method adoption highlights the importance of industry input, so a Participatory Design (PD) approach was taken in developing VBRE, iteratively evaluating and refining the method with input from practising analysts. A series of complementary evaluations of the method are presented. An experimental study investigated the method's utility and usability with computer science undergraduate students, whilst a set of four case studies explored adoption of the VBRE method with industry analysts. The analysts used the method during their RE work, adapting the approach according to their circumstances and levels of experience. The participants credited the method with a positive impact on their RE work and the novice analysts reported feeling more confident of their abilities to handle 'soft issues'.The key contributions of this work are:1. An exploration of the views of practising analysts as to the relevance and impact of VM&Es within their RE work.2. Development of an analysis method and support materials to aid analysts in identifying users' VM&Es.3. A demonstration of the utility of adopting a PD approach to the development of RE methods.4. An evaluation of the use of the method in industry, exploring the use of case studies to understand how novice and expert analysts adopt and adapt the VBRE approach.This thesis is unusual in taking a PD approach to developing a solution for a RE problem: that analysts need to understand users' VM&Es and their impact on software projects. The VBRE method attempts to address this gap, and the positive reception given by the analysts involved in evaluation of the method indicates they see utility in the approach. Future work will focus on continuing to collaborate with industry analysts to understand their use of the VBRE method, identifying improvements to the method and website, and gathering examples of the method's impact.