*We apologize for cross-posting* Dear Colleagues, We invite your participation at the 9th AAAI Conference on Human Computation and Crowdsourcing (HCOMP 2021) to be held virtually, *November 14-18, 2021*. HCOMP is the home of the human computation and crowdsourcing community. It is the premier venue for presenting the latest findings from research and practice into frameworks, methods and systems that bring together people and machine intelligence to achieve better results. The conference invites various types of submissions for full research papers, Blue Sky Ideas, workshops to be held at the conference, and works-in-progress and demos. The conference also invites submission to the Graduate Consortium and to CrowdCamp, two events that complement the main conference. The full Call for Papers is available at https://www.humancomputation.com. Please note the upcoming deadlines: June 25, 2021: Abstract submission (required to submit a full paper) July 2, 2021: Full papers due August 20, 2021: Notification of acceptance September 3, 2021: Final camera-ready papers due Electronic abstract and paper submission through the HCOMP-21 EasyChair paper submission site (https://easychair.org/conferences/?conf=hcomp2021) is required on or before the deadlines listed above. Please contact us at hcomp21@aaai.org if you have any questions. We look forward to your participation at HCOMP 2021 this fall! - The Organizing Committee for HCOMP2021 Website: https://www.humancomputation.com Twitter: @hcomp_conf