In April, FamilySearch announced that Latter-day Saint users of FamilySearch.org will be able to receive free access to Ancestry.com, findmypast, and MyHeritage.

Invitations to sign up for these three sites will be sent by email to members of the Church over the next few months.

Update June 5, 2014: This post previously recommended that you change your name and email settings in FamilySearch.org in preparation for receiving your invitation. I have confirmed with FamilySearch that these steps are not necessary.

When you receive your email invitation, it will explain how to register for your personal account. The invitation e-mail will only work for the member who receives it.

For more information see LDS Member Access to Partner Family History Websites.