The Institute for Diversity and Ethics in Sport study, which grades professional leagues on the number of participating women and minorities, shows women own three WNBA teams, up two from 2007.
The number of minority head coaches and players increased, but there was a slight decrease in women and minority assistant coaches.
Lapchick, director of the University of Central Florida institute, said the WNBA has long led the way in his studies and benefited from its relative youth.
The league began play in 1997.
''They started at the same time the [NBA] began its diversity initiative, so the WNBA was able to include a good pool of candidates from the very beginning,'' Lapchick said.
The WNBA said it had no comment on the study. Carla Christofferson and Katherine Goodman own the Los Angeles Sparks, Colleen J. Maloof and Adrienne Maloof-Nassif own the Sacramento Monarchs, and the Seattle Storm's owners are Anne Levinson, Ginny Gilder, Dawn Trudeau and Lisa Brummel.
There are now as many teams with women holding a partial or full stake in a WNBA team as there are in the NFL and more than in any other sport. Women own all or part of the St. Louis Rams, San Francisco 49ers and Jacksonville Jaguars in the NFL and the Sacramento Kings and Washington Wizards of the NBA. Major League Baseball has no female majority ownership.
Of the WNBA's 14 teams, five had female head coaches: Linn Dunn of the Indiana Fever, Pat Coyle of the New York Liberty, Jenny Boucek of the Sacramento Monarchs, the Houston Comets' Karleen Thompson and the Atlanta Dream's Marynell Meadors.