This work describes associations of Thiara (Tarebia) granifera, its larval trematode community, and Chaetogaster limnaei limnaei at a freshwater reservoir in Jamaica. Larvae of 2 trematodes were present, i.e., a notocotylid (15.3%) and Philophthalmus sp. (1.3%), in 3,575 T. granifera examined. The prevalence of both infections increased with snail shell length (H  =  56, P < 0.01, H  =  23.1, P < 0.01, respectively). Only 3.0% (n  =  595) of infected snails possessed reproductive stages, compared with 90.3% (n  =  2,980) of uninfected snails (χ²  =  2,059.8, df  =  1, P < 0.001); both trematodes negatively impacted snail reproduction. Chaetogaster l. limnaei occurred within the mantle cavity of T. granifera with a prevalence of 2.3% (n  =  3,575); intensity ranged from 1 to 6 annelids. Notocotylid larvae occurred in 32.5% (n  =  83) of snails also harboring C. l. limnaei, compared with 14.9% (n  =  3,492) of snails lacking the annelid (χ²  =  18.127; P < 0.001). Chaetogaster l. limnaei appears not to influence the recruitment of egg-transmitted, notocotylid infections to snails. Ingestion of emergent cercariae by the annelid was observed; this may impact transmission of the parasite. The article presents the first report of a notocotylid and C. l. limnaei in T. granifera, and of Philophthalmus sp. in Jamaica.