Informed by the ‘assembly’ jurisprudence of the United Nations Human Rights Committee, this article addresses fundamental questions about the meaning and scope of ‘assembly’ in Article 21 of the International Covenant on Civil and Political Rights (ICCPR). In seeking to determine when the right of peaceful assembly might properly be engaged, the article explores the interrelationship of assembly with expression and association and proposes a definition of ‘assembly’—for the purposes of its protection—as ‘an intentional gathering by two or more people (including in private and online/virtual spaces)’. Such definitional reflection is particularly timely in light of the Human Rights Committee's drafting of General Comment No 37 on Article 21.