After moving to Washington, D.C. in 1948, Chinnis joined and served in leadership positions at the Episcopal Church of the Epiphany.

Her growing involvement in the Episcopal Church included election as president of the diocesan chapter of Episcopal Church Women, serving as presiding officer of the national ECW's Triennial Meeting in 1976.

Chinnis served in a wide variety of church organizations, including the cathedral chapter of Washington National Cathedral, vice president of Province 3, the mid-Atlantic region of the Episcopal Church, vice chairwoman of Executive Council, which governs the church between General Conventions, and vice president of General Convention.

Chinnis also has served as a member or delegate to numerous Anglican and ecumenical bodies: She was a member of Mortar Board (Virginia Alpha chapter at the College of William & Mary).

For 13 years through 1983 Chinnis was trustee and treasurer of the Mortar Board National Foundation.