Capen Street station is a light rail station in Milton, Massachusetts. It serves the MBTA Ashmont–Mattapan High Speed Line. It is located on Capen Street off Eliot Street; the westernmost of the four MBTA stations in Milton, it consists of two side platforms flanking the eponymous street's grade crossing. The platforms are staggered to allow trains to make the stop at Capen Street before crossing the street itself, as there is no signal at the grade crossing. Capen Street is accessible via wooden ramps on both platforms. Capen Street opened in September 1930 as an infill station on the line.

The Ashmont–Mattapan High-Speed Line, commonly referred to as the Mattapan Trolley, is a partially grade-separated light rail line which forms part of the MBTA's Red Line rapid transit line. The line, which runs through Boston and Milton, Massachusetts, opened on August 26, 1929, as a conversion of a former commuter rail line. It exclusively uses PCC streetcars built in the 1940s. Passengers must transfer at Ashmont to access the rest of the Red Line, which uses heavy rail metro rolling stock.