US Census Bureau
Us Census Bureau: American Family [Pdf]
The US Census Bureau measures the demographic changes and characteristics of the American Family from the 2000 Census.
Other
Definition of "Family" in Zoning Law and Building Codes
Site offers guidelines to writing a definition of Family for the purposes of zoning laws. Gives constitutionally permissible standards.
CommonLit
Common Lit: Themes: Friendship & Family: What Makes a Family?
This is a collection of Grade-Leveled texts (3-12) to address the question, "What makes a family?" Select a grade level and a collection of on grade-level reading passages on the topic comes up. [Free account registration required for...