The Walton Family Foundation will pour $7.5 million into the site GreatSchools, which offers parents information and reviews of schools across the country.

Walton has already invested $13 million since 2004 in the site, whose parent organization estimates that it served 44 million viewers last year.

[UPDATE: GreatSchools has given me new information on how the funding will affect the information presented on the site. I’ve reworded this section to reflect what they’ve said. The new money will support an increase in the number of “crowdsourced” reviews of schools from parents and community members, so that more than half of the schools profiled will have 10 or more reviews by 2015. At present, just 19 percent of schools on the site have 10 or more reviews linked to them.]

The cash influx will also support the site’s use of students’ academic growth data in its school ratings, a feature that is currently only offered for reviews of schools in certain cities, such as Indianapolis, Milwaukee, and Washington. Twenty-five percent of the school ratings will have that feature—up from just 1 percent now, GreatSchools officials say.

GreatSchools, which is run by a San Francisco-based nonprofit, was founded in 1998, and today it touts profiles of 200,000 schools, with one million parent ratings and reviews.

The site has drawn major support from a variety of education-focused philanthropies and organization, including not only Walton, but the Robertson Foundation and the Bill and Melinda Gates Foundation. (Walton supports Education Week’s coverage of parent-empowerment issues, and Gates backs the newspaper’s coverage of industry and innovation.)

GreatSchools rates traditional public, charter, and private schools on a scale of 1-10—though its appeal to users also comes in readers’ access to comments about schools, favorable or not, posted by teachers, students and others. See my colleague Christina Samuels’ story from last year about GreatSchools’ mission and growth.