<p>The decreasing frequency of extreme cold events is driving mangrove encroachment into temperate salt marshes, altering the ecosystem service portfolio provided by these critical habitats. Straddling temperate and subtropical regions, Florida (USA) is at the forefront of mangrove encroachment and the only mainland U.S. state with mature mangrove forests, making it a critical case study of tropicalization. To assess potential ecological impacts caused by mangrove encroachment, we performed a systematic review of studies which quantified ecosystem service delivery in Florida salt marsh, mangrove, and transition habitats. The overall objective of this review was to identify — if present — common trends or recurring outcomes resulting from mangrove encroachment, highlighting tradeoffs or results which may predictably occur in encroached marshes. We reviewed 32 studies and extracted data describing ecosystem service delivery and study design. Carbon sequestration (19 studies), water purification (10 studies), and coastal food webs and fisheries (9 studies) were the most studied services, with others (e.g., coastal protection) receiving little or no attention. Research was concentrated in several locations in Florida and focused largely on black mangroves and smooth cordgrass. Although we found agreement among studies regarding metrics like carbon storage, generalizations and straightforward estimates of service increase or decrease were challenging due to context-specificity and diverse experimental designs. Standardized experimental frameworks could address these challenges and support management of marshes undergoing encroachment in Florida and beyond.</p>