This　study　explores　how　Transactive　Memory　System　(TMS)　contributes　to　breakthroughs　in　inventor　teams.　From　the　perspective　of　knowledge　integration,　a　TMS　plays　a　crucial　role　in　optimizing　diverse　expertise,　facilitating　effective　knowledge　sharing　and　integration,　and　creating　innovation　synergy　essential　for　breakthroughs.　We　argue　that　the　three　dimensions　of　TMS—specialization,　credibility,　and　coordination—differently　influence　breakthroughs　due　to　their　distinct　roles　in　knowledge　integration　within　the　team.　Using　the　U.S.　pharmaceutical　patent　data,　we　identify　an　inverted　U-shaped　relationship　between　specialization　and　breakthroughs,　as　well　as　positive　relationships　between　credibility　and　breakthroughs,　and　between　coordination　and　breakthroughs.　These　relationships　are　moderated　by　technological　complexity　and　inventor　team　size.　By　leveraging　objective　patent-based　proxies　for　TMS,　our　study　provides　empirical　evidence　on　its　nuanced　mechanisms　and　contextual　contingencies,　offering　new　insights　into　the　micro-foundations　of　team-based　R&D　collaborations　and　practical　guidance　for　fostering　breakthrough　technologies.　©　2025　Elsevier　Inc.