Experimental Validation of a Risk Assessment Method -- Supporting the Validation of Adequacy in Requirements-based Hazard Mitigations -- Evaluating Feature Models: A Goal-Question-Metric Study at Opel -- Modeling and Reasoning about Information Quality Requirements -- Detecting and Correcting Outdated Requirements in Function-Centered Engineering of Embedded Systems -- Estimating the Implementation Risk of Requirements in Agile Software Development Projects with Traceability Metrics -- The Role of Catalogues of Threats and Security Controls in Security Risk Assessment: An Empirical Study with ATM Professionals -- Analyzing and Enforcing Security Mechanisms on Requirements Specifications -- From Stakeholder Requirements to Formal Specifications through Refinement -- Towards More Efficient Requirements Formalization: A Study -- How Artifacts Support and Impede Requirements Communication -- Consonance between Networked Economic and IT Services: Finding the Balance Between Conflicting Requirements -- The Emerging Requirement for Digital Addiction Labels -- Challenges of the customer organizations requirements engineering -- (RE) process in the outsourced environment A case study -- A Case Study Evaluation of the Guideline-Supported QUPER Model for Elicitation of Quality Requirements -- Towards Crowd-based Requirements Engineering -- Functional Requirements Modeling for Interactive TV Applications -- Flexi View: A Magnet-Based Approach for Visualizing Requirements Artifacts -- Requirements Engineering in the Bidding Stage of Software Projects A Research Preview -- A Systematic Literature Review of Requirements Prioritization Criteria -- Embedding Stakeholder Values in the Requirements Engineering Process -- Supporting Requirements Feedback Flows in Iterative System Development -- User-Constrained Clustering in Online Requirements Forums.

This book constitutes the refereed proceedings of the 20th International Working Conference on Requirements Engineering: Foundation for Software Quality, REFSQ 2014, held in Essen, Germany, in April 2013. The 23 papers presented together with 1 keynote were carefully reviewed and selected from 62 submissions. The REFSQ'15 conference is organized as a three-day symposium. The REFSQ'15 has chosen a special  conference theme "I heard it first at RefsQ". Two conference days were devoted to presentation and discussion of scientific papers. The two days connect to the conference theme with a keynote, an invited talk, and poster presentations.There were two parallel tracks on the third day: the Industry Track and the new Research Methodology Track. REFSQ 2015 seeks reports of novel ideas and techniques that enhance the quality of RE's products and processes, as well as reflections on current research and industrial RE practices.