Lehrer obtained B.A. degrees in Music and Mass Communications from the State University of New York at Albany. While a student there, he hosted a radio program on the college radio station WSUA which has become WCDB Albany. He holds a Master of Public Health degree from the Columbia University Mailman School of Public Health and a masters degree in Journalism from Ohio State University. Lehrer resides in Inwood, Manhattan with his wife and two sons.

Lehrer has been hosting his show, originally called "On The Line," since its inception in 1989. The format is interviews with newsmakers, combined with listener phone calls. Newsmakers are local, national and international, often authors on book tours, or metropolitan area politicians, including both of New York's senators, and most congress, state and city representatives from the New York, New Jersey and Connecticut area. But sometimes guests are less-famous individuals affected by the news, like Brooklyn residents on the site of giant housing developments, or neighbors of noisy Manhattan night clubs. Frequent topics are housing, health care, transportation, education, and other government functions, the arts, the experience of living in New York and the surrounding area, and international affairs, such as the Iraq war or Israel/Palestinian conflict, particularly from a New York perspective. His programs often use The New York Times for leads and guests. He tries to maintain a balance between issues as they affect listeners, and "horse-race" pundit discussions of politics.

In February 2009, Executive Producer Nuala McGovern, who was leaving the program, compiled a selection of the greatest moments on the program since she started in 2000, and gave "five secrets for producing a talk show."

Rule No. 1 is, "accept that you're going to have to break a few eggs in the name of public service." Sometimes you have to ask that tough question "that may not be what the guest wants."

For example, in 2003, Lehrer interviewed Iraqi foreign minister Adnan Pachachi, part of the first provisional government of Iraq. A caller from Iraq said that he would not recognize the Iraqi government because it was installed by the American government. Pachachi answered the question, but angrily responded, "I find it extraordinary that you allow people like that to use these airways."

In another example, Lehrer asked Supreme Court Justice Sandra Day O'Connor, "Why did you deny the state of Florida the right to recount votes in its own state?" This was appropriate, he said, because 75% of the New York vote went for Al Gore in the 2000 election.

Rule no. 2 is, "be ready to turn on a dime." For example, during the New York City blackout, the station's main power went out.

Rule no. 3 is to screen the call-ins carefully. For example, when a caller said that Senator Hillary Clinton was anti-military and required all the military officers in the White House to wear civilian clothes, not uniforms, McGovern saw that Senator Clinton herself was calling in to deny it.

Rule No. 4 is that "research" includes getting out and talking to people. "Taxi drivers are a font of information." If a subject provokes discussion, "it's probably going to work on the radio." For example, one successful subject is parenting kids in the City. One successful segment was about a mother who allowed her 9-year-old son to travel alone on the subway.

Rule no. 5 is, "Know thy audience." Audience call-ins are an important resource for good programs. Successful call-ins were about first-time voters, how it is to live with HIV, how religion affects your politics, your environmental sins, losing your job. One listener suggested renaming "Citi Field" to "Debits Field."