TL;DR: The highest-lift community engagement formats in 2026 are polls (3.8x more interactions), AMA sessions (+42% weekly activity), image posts (2.4x engagement), and daily moderator participation (lifts 61% of communities). Below are 50 field-tested ideas organised by effort level, so you can fill a month of content in one sitting. An empty community calendar is the #1 killer of new groups —...