California's attorney general on Tuesday announced the agreement with Match.com, eHarmony and Spark Networks.
She says the companies signed a joint statement of principles that include checking subscribers against national sex offender registries, providing a rapid way to report abuses and providing members with safety tips.
The statement is non-binding but the companies say they hope it will set an example for other dating sites.
Attorney general's spokeswoman Lynda Gledhill says the agreement was inspired by the case of a woman who was assaulted in 2010 by a man she met through Match.com. Alan Wurtzel had previous sexual battery convictions.