Leppert served on the Board of Directors of Washington Mutual, the United States' largest savings and loan association, at the time of its seizure by the FDIC on September 25, 2008 (with most of its functional assets sold in a government-negotiated arrangement to JP Morgan Chase). It was the largest bank failure in U.S. history.
Leppert has also held positions at McKinsey & Co., Trammell Crow Company, Pacific Financial Corporation, and Castle & Cooke Properties, Inc.
Leppert received the 2006 Global Cross Millennium Award for Corporate Environmental Leadership and a Torch of Conscience award from the American Jewish Congress.
The Leppert campaign condemned anti-gay robocalls targeting Ed Oakley and urged the Heritage Alliance PAC to cease making such calls. Had he been elected, Oakley would have been the first openly-gay mayor of a top ten U.S. city.
Leppert was appointed as a White House Fellow by President Ronald Reagan; in this role he served in the Department of the Treasury and White House Staff.
In January 2008, Mayor Leppert embarked on a trade mission to Monterrey, Mexico, to promote Dallas's medical, educational, and corporate institutions. Another part of the trip's agenda was to lobby for an inland seaport for the Dallas area. Leppert was joined by more than a dozen officials from city government, the Dallas Independent School District and various health care and commercial institutions in the largest mission of its kind in years. One of the agreements reached on the trip include a plan for an MD/PhD program in Mexico provided by UT Southwestern Medical School. Leppert also stated that Mexican President Felipe Calderon would be visiting Dallas on his next visit to the United States.
Following his trip to Mexico, Leppert led a trade mission to China and signed "friendship city" agreements with major industrial cities such as Dalian and Qingdao.
On February 21, 2008, Leppert unveiled The Every Child Ready to Read @ Dallas program. The latest program was part of Leppert's larger plan to improve Dallas's education system which was unveiled in 2007. Leppert also donates his mayoral salary to a scholarship fund for students from low-income families.
On May 17, 2008, Leppert received an honorary doctorate from his undergraduate alma mater, Claremont McKenna College, for which he serves as a trustee. Leppert told graduates to "know your principles" and encouraged them to write them down. "This may sound simple and obvious, but over the course of a lifetime, it may be one of the most difficult promises you ever keep. I know I am confronted by this each and every day. Simply stated, using generic terms like honesty and integrity are not near enough[...] People rarely get in trouble or lose their compass in one fell swoop... it is a series of small compromises, missteps that lead to a landslide... and a lost sense of self. In the same speech, Leppert called his visit to Auschwitz a "single day [that] changed the way I looked at the world."