David King is a senior lecturer in public policy at Harvard University in Cambridge, Mass.

Bike & Brunch is a Jewish, largely single bicycling group in the Baltimore-Washington, D.C., region.

Janet Porter is the president and founder of Faith2Action, a Christian advocacy group that works to influence politics and legislation. The group is based in Dania Beach, Fla.

J.J. Adler directed the 2007 documentary Unattached, about single Orthodox Jews in New York City. Watch the trailer.

Advance USA promotes Judeo-Christian religious values. It is based in Independence, Mo., and maintains a Washington, D.C. office.

The Unitarian Universalist Association of Congregations works to connect individual congregations with others across the U.S. Contact the executive assistant for the office of the president, Stephanie Carey Maron.

Neil Clark Warren, a psychologist and former dean at Fuller Theological Seminary, co-founded and chairs the eHarmony online dating service. He has written several books about relationships, including Date … or Soul Mate?: How to Know if Someone Is Worth Pursuing in Two Dates or Less.

Christian Piatt is the co-author of MySpace to Sacred Space: God for a New Generation (2007) along with his wife Rev. Amy Piatt. He is an author, editor, speaker, musician and spoken word artist. He co-founded Milagro Christian Church in Pueblo, Colorado with his wife in 2004. Contact through the form on his website.

May Vanderbilt of San Francisco is a co-author of the Good Girl line of novels, including the 2007 title The Book of Jane, about single Christian women navigating modern life.