The rise of mobile, social and cloud apps pose new challenges and opportunities for requirements engineering (RE). Traditional RE techniques have difficulties scaling for (software) product with thousands to millions of users, who form a large and heterogeneous group that can be denoted as a crowd. Researchers have identified several issues with applying RE in the new crowd paradigm. Initial methods and tools are being investigated, but we see the need for more tailored and holistic approaches focusing on Crowd-Based Requirements Engineering. The Second Workshop on Crowd-Based Requirements Engineering (CrowdRE 2017) builds on the success of its first edition, which achieved the unification of visions into a coherent RE approach. It aims to attract papers with novel and innovative ideas on CrowdRE, and to facilitate interactive discussions between scientists and industry representatives to define a roadmap for CrowdRE, assess its role in the software development lifecycle, and work towards a shared base of CrowdRE resources.