The Brown Line (Ravenswood Service) of the Chicago Transit Authority Chicago 'L' rapid transit system, is an 11.4 mile route with 19 stations between Albany Park on the north and downtown Chicago. It runs completely above ground and is one of CTA's busiest rail lines, serving more than 66,000 passengers each weekday. The Brown Line runs completely within the city limits of Chicago, Illinois.

The Brown Line operates to the Loop weekdays and Saturdays from about 5am to 12:30am and on Sundays from 7am to midnight. The Brown Line Shuttle service, running only between the northern terminus Kimball and Belmont, runs from about 4am to 5am and about 12:30am to 2:30 am on weekdays and Saturdays, and about 5am to 6am and about midnight to 1am on Sundays. At Belmont, southbound riders can transfer to the 24-hour Red Line.

Before CTA lines were color-coded in 1993, the Brown Line was known as the Ravenswood Route; specifically, the series of stations from Belmont to Kimball were called the Ravenswood branch. Accordingly, the Kimball-Belmont shuttle service was called the Ravenswood Shuttle. Some Chicago transit riders and historians still refer to the line by those names.