MD 28 continues southeast along the southern edge of Gaithersburg and passes by the new urbanist development Kentlands. The highway crosses Muddy Branch parallel to a pair of spurs on the south designated MD 899 (American Way). After the state highway expands to six lanes and intersects Muddy Branch Road, the old alignment of MD 28, Darnestown Road, splits to the east and MD 28 veers northeast as Key West Avenue. The state highway intersects MD 119 (Great Seneca Highway); passes to the north of the Montgomery County campus of Johns Hopkins University, the Universities at Shady Grove, and Shady Grove Adventist Hospital, and enters the city of Rockville at its intersection with Shady Grove Road, where the highway's name changes to Montgomery Avenue. MD 28 curves south through the western part of Rockville and meets the western end of Gude Drive, which provides a bypass of downtown Rockville, and the eastern end of Darnestown Road. The highway curves east again and crosses Watts Branch within its seven-ramp partial cloverleaf interchange with Interstate 270 (Eisenhower Memorial Highway).