Liam Neeson as Alfred Kinsey

Laura Linney as Clara McMillen

Chris O'Donnell as Wardell Pomeroy

Peter Sarsgaard as Clyde Martin

Timothy Hutton as Paul Gebhard

John Lithgow as Alfred Seguine Kinsey

Tim Curry as Thurman Rice

Oliver Platt as Herman Wells

Dylan Baker as Alan Gregg

Julianne Nicholson as Alice Martin

William Sadler as Kenneth Braun

John McMartin as Huntington Hartford

Veronica Cartwright as Sara Kinsey

Kathleen Chalfant as Barbara Merkle

Heather Goldenhersh as Martha Pomeroy

Dagmara Dominczyk as Agnes Gebhard

John Krasinski as Ben

Arden Myrin as Emily

David Harbour as Robert Kinsey

Luke Macfarlane as Bruce Kinsey

Jenna Gavigan as Joan Kinsey

Judith Polson as Mildred Kinsey

Leigh Spofford as Anne Kinsey

Benjamin Walker as Kinsey (Age 19)

Matthew Fahey as Kinsey (Age 14)

Will Denton as Kinsey (Age 10)

Harley Cross as Young Man in Gay Bar

Katharine Houghton as Mrs. Spaulding

Lynn Redgrave as Final Interview Subject

Jarlath Conroy as Grocer

Jason Patrick Sands as Male Student #1

Marcel Simoneau as Male Student #2

Bobby Steggert as Male Student #3

Johnny Pruitt as Male Student #4