CAPE ELIZABETH — The town’s Democratic Committee tonight nominated Kim Monaghan-Derrig as its candidate in a special election to fill a vacancy in Maine House District 121.

Monaghan-Derrig, a lifelong Cape Elizabeth resident, works in the marketing field, serves on the town school board and has a background in economic development. She is pursuing her master’s degree in public policy at the Muskie School in Portland.

She will compete against Republican candidate Nancy Thompson, an insurance agent and 25-year resident of Cape Elizabeth with a record of community service.

The special House election on Aug. 16 will fill the seat vacated by Cynthia Dill. The Democrat left her House seat to run for an open state Senate seat, to which she was elected.