In 1977, Richmond voters elected Lambert as one of the six members representing the 33rd district in the House of Delegates. He began serving in the part-time position in 1978, and was re-elected several times, although the district boundaries changed after the 1980 census to include east-central Henrico county and part of
Charles City County and the new single-member district was renumbered the 71st. He served alongside
George E. Allen Jr.,
Walter H. Emroch,
Franklin P. Hall and
James S. Christian Jr., all fellow Democrats. Lambert also helped expand the scope of services that fellow optometrists could provide, and worked to limit deleterious professional effects of retail interests. His wife Carolyn also assisted in various legislative committees. In 1985, voters from parts of Richmond and all of Charles City County elected Lambert to the Virginia Senate in a special election, where he succeeded
Douglas Wilder, who had become
Lieutenant Governor of Virginia and represented the 9th Senate District. He was re-elected several times and rose in seniority for decades. Fellow democrat and lawyer
Jean Wooden Cunningham succeeded him as the District 71 delegate in the session which began January 8, 1986, and would win re-election many times. Lambert was the first African-American in the 20th Century to serve on the Virginia Senate Finance Committee. During his senate tenure, Lambert served on a number of other committees as well, including Education and Health, General Laws, Privileges and Elections, General Government, and Health and Human Resources. Additionally, he chaired the Subcommittees on Higher Education and General Government, the Brown v. Board Scholarship Commission (assisting students who would have attended schools closed to prevent desegregation during Massive Resistance), and the Lead Abatement Subcommittee. He became known for his efforts to bridge party lines, and on behalf of education. The following year, Senator Lambert was defeated for re-election by former Delegate
Donald A. McEachin, who made the Allen endorsement a key factor in the contest. ==Death and legacy==