The Southern Secondary is a rail line in New Jersey, operated by Conrail Shared Assets Operations (CSAO) from South Amboy to Red Bank, and the Delaware and Raritan River Railroad (DRR), a subsidiary of Chesapeake and Delaware, LLC, between Red Bank and Lakewood.

From 1879, the line was owned by the Central Railroad of New Jersey (CNJ), which used it as their Southern Division, which, at its greatest extent, ran from Red Bank to the shores of the Delaware Bay at Bivalve and Bayside.

In 1976, Conrail took over all operations, and in 1978, it severed the line between Woodmansie and Winslow Junction, ending its use as a through route linking South and North Jersey.

The Delaware and Raritan River Railroad assumed common carrier operations between Red Bank and Lakewood as of July 1, 2022.

The Delaware & Raritan River Railroad serves customers between Earle and Lakewood, with cars coming from Jamesburg via the Freehold Secondary.