In addition to her professional achievements, Attorney Brennan previously dedicated much of her time to the community. She was a member of the Greater Hazleton Chamber of Commerce, where she served on the Women's Networking Committee, and the Abington Business & Professional Association in northern Lackawanna County.

She has been a volunteer on the United Way's allocations committee since 2005 and currently serves as a panel committee chair.

She was a board member and past board chair of the Volunteer Center of Greater Hazleton, Inc., was the Community Board chair of its predecessor (Volunteers of America of Greater Hazleton), and had been a member of the Advisory Board of Volunteers of America.

She also served as a board member of the United Way of Greater Hazleton; the Helping Hands Society of Luzerne, Carbon and Schuylkill Counties; and the Hazleton Chapter of the Penn State Alumni Association.

Her service to these organizations went beyond her board membership. Attorney Brennan was the tournament director for the Helping Hands Society’s annual volleyball tournament from 1994 through 2006 and has volunteered with the annual Helping Hands telethon since 1993. She served as chair of the annual business meeting of members of the Penn State Hazleton Alumni Chapter for three years and was the Membership Committee chair. She also chaired the Volunteer Center's annual Celebrating Mothers event, which is the organization's largest annual fundraiser. In addition, she participated in numerous nonprofit events throughout the year for all of these mentioned organizations, as well as many others.

She previously served on the boards of MMI Preparatory School in Freeland, PA; the Greater Hazleton Association of Realtors; and the Hazleton Area Landlords Organization, where she also served as its solicitor.

Her service to the community was recognized in 2008 by the Volunteer Center of Greater Hazleton, which presented her with the GEMS Award - Going the Extra Mile in Service.