Alternate Concepts, Inc. (ACI) is a transit management company within the United States.

[1] Between 2003 and 2014, ACI also operated the Massachusetts Bay Transportation Authority's commuter rail system.

[2] Additionally, Alternate Concepts is planned to operate MTA Maryland's Purple Line.

[3] Alternate Concepts was founded in 1989 by three former employees of the Massachusetts Bay Transportation Authority, James F. O’Leary, Richard Brown and Jane Daly.

[1] Alternate Concepts currently manages and operates the following rail services:[4] This United States railway company-related article is a stub.