<p>This book constitutes the workshop proceedings of the 21st International Conference on Database Systems for Advanced Applications, DASFAA 2016, held in Dallas, TX, USA, in April 2016.</p><p>The volume contains 32 full papers (selected from 43 submissions) from 4 workshops, each focusing on a specific area that contributes to the main themes of DASFAA 2016: The Third International Workshop on Semantic Computing and Personalization, SeCoP 2016; the Third International Workshop on Big Data Management and Service, BDMS 2016; the First International Workshop on Big Data Quality Management, BDQM 2016; and the Second International Workshop on Mobile of Internet, MoI 2016.</p><div><br></div>