In 1987, Montgomery switched careers to work in the non-profit sector for a number of organizations including the Olney Theatre Center, Arts for the Aging, and the Arthritis Foundation, from which she retired in 1999.

Both prior to and since her election to public office, Montgomery has volunteered with a variety of community organizations related to the arts, women's issues, and people with developmental disabilities.

[1] One of her children has autism, which has driven Montgomery's involvement in community organizations that serve people with developmental disabilities, and her political advocacy related to the issue.

[2] In 2009, Montgomery worked to limit state budget cuts to mental health programs and services to people with developmental disabilities.

[4] In addition to her work on behalf of people with developmental disabilities, Montgomery has been active on health care, good government, and environmental issues.

In October 2023, the Brookeville Bypass along Maryland Route 97 was officially dedicated to Montgomery and former Brookville town commissioner Clyde Unglesbee.