This　study　examines　the　manifestations　and　mediating　factors　of　agency　for　research　among　four　Chinese　university　foreign　language　teachers　through　an　activity　theory　lens.　Using　a　multiple　case　study　approach,　data　from　interviews,　journals,　documents,　and　profiles　were　analyzed　via　the　constant　comparative　method.　Findings　reveal　teacher　agency　for　research　manifests　through　three　interconnected　dimensions:　agency　beliefs,　agency　practice,　and　agency　disposition.　Second,　these　manifestations　of　teacher　agency　for　research　were　mediated　by　various　elements　within　the　research　activity　system.　Specifically,　at　the　subject　level,　university　foreign　language　teacher　agency　for　research　was　mediated　by　research　competency　and　motivational　factors.　The　mediational　tools　comprised　social　interactions,　cultural　artifacts,　and　activity　structures.　Object-oriented　mediation　was　evidenced　through　the　enhancement　and　cultivation　of　teacher　agency　for　research　via　evolving　objectives　across　different　research　activities.　Furthermore,　the　institutional　rules,　community　dynamics,　and　division　of　labor　collectively　constituted　the　socio-cultural　context　that　mediated　teacher　agency　for　research.　The　study　contributes　to　understanding　how　EFL　teachers　navigate　dual　teaching-research　roles　in　higher　education　contexts　where　research　productivity　is　increasingly　emphasized　and　substantively　to　the　existing　body　of　knowledge　on　teacher　agency.