Deprescribing is a clinically important and feasible innovation that ensures medication efficacy, reduces harms, and mitigates polypharmacy. It involves reducing doses or stopping medications that are not useful, no longer needed, or which may be causing harm. It may also involve changing to a safer agent or using non-pharmacological approaches for care instead. Clinical guidelines combined with behaviour changes (of health care providers (HCPs), the public, and health care decision-makers) are needed to integrate deprescribing into routine practice. Using rigorous international standards, the Bruyère Research Institute Deprescribing Guidelines research team validated a ground-breaking deprescribing guideline methodology and developed or co-developed 5 evidence-based deprescribing guidelines. In March 2018, the team hosted an international symposium convening HCPs, researchers, public agencies, policymakers, and patient advocates in Ottawa, Ontario, Canada. This 3-day symposium aimed to facilitate knowledge exchange amongst guideline developers, users, and the public; initiate partnerships and collaborations for new deprescribing guideline recommendations and effectiveness research; and to continue work on HCP deprescribing education activities. An interprofessional planning committee developed an overall agenda, and small groups worked on session objectives and formats for different components: methods for rigorous deprescribing guideline development, implementation experiences, research/evaluation experiences and educational needs. Through a series of keynote speakers, panel discussions, and small working groups, the symposium provided a forum for participants to meet one another, learn about their different experiences with deprescribing guidelines, and develop collaborations for future initiatives. One hundred thirty participants, from 10 countries and representing over 100 institutions and organizations took part. Symposium proceedings are presented in this issue of RSAP for sharing with the wider community engaged in the care of patients with problematic polypharmacy.