Clark announced her resignation Tuesday at a school board meeting. The move takes effect Aug. 12.
She has represented District 6 in central Raleigh for 10 years, and her current term runs through 2011.
School board members Eleanor Goettee, Patti Head and Lori Millberg have already chosen not to run for re-election this fall, and school board Chairwoman Rosa Gill was recently named to the state House to finish the term of former state Rep. Dan Blue, who moved to the Senate following the death of Sen. Vernon Malone.
Horace Tart is the only incumbent school board member on the ballot this fall.