It's the third time in four years the school has earned the category's top slot. Dartmouth earned the honor last year.
The University of Utah comes in at No. 6 on the 2009 family friendly list.
The rankings are based on student responses to questions about how happy married students are, how much the school does for spouses, how helpful it is to students with children and how many students have children.
Princeton Review is the same company that has named BYU the nation's most "stone-cold sober" school for 11 straight years.