Terrell has worked in the area of voting system reform in this country and abroad, traveling in 1993 to New Zealand to support that country's successful referendum to adopt a proportional voting system. She also directed the research for several reports produced by FairVote, including analyses of the 1994 and 1996 congressional elections and the 1992 presidential elections.
Before helping to found FairVote, Terrell worked extensively as a political consultant around the country, working as campaign manager and field director for campaigns for the U.S. President, U.S. House and U.S. Senate, for governor and for state and city-wide initiative efforts. Among these campaigns were a proposed equal rights amendment in 1992 to the Iowa state constitution, the 1992 presidential campaign of Sen. Tom Harkin, Douglas Wilder's 1989 gubernatorial victory in Virginia and former Congresswoman Jolene Unsoeld's congressional campaign in 1990. Terrell also researched the state initiative process for the Fund for the Feminist Majority.
Terrell is a mother of three children and active in civic affairs in Takoma Park, Maryland. She graduated with a B.A. in political science from Swarthmore College in 1986.