Koslowitz's parents immigrated to the United States from Kraków, Poland, settling in the Soundview section of the Bronx.

She entered public service as a Legislative Aide for Congressman Gary Ackerman (D-NY), and subsequently for New York Council member Arthur Katzman.

She then became the full-time Special Assistant and Queens Ombudsman to City Council President Andrew Stein.

In 2001, Koslowitz stepped down because of term limits, remaining in government as an appointed Deputy Borough President for Queens.

This was in opposition to John Dereszewski, head of Community Board 6's Transportation Committee, who said that while he supports “90 percent of the things that are going to be done,” he couldn't back the proposal because of the loss of nearly 200 parking spaces.