The set of business principles for the industry, which are also meant to screen out fraudsters, additionally includes providing customers with means to rapidly report abuse.
The companies said they have already taken similar steps to protect their customers, even before the public announcement was made on Tuesday.
California Attorney General Kamala Harris reached the agreement with the companies after establishing an eCrime Unit last year to prosecute identity theft, data intrusion and crimes involving the use of technology.
"The safety of our members and integrity of our sites is of fundamental importance to us, and we have always taken a multi-faceted approach to creating and maintaining safe online communities like JDate and ChristianMingle," Greg Liberman, president and CEO of Spark Networks, said in a statement.
Jeremy Verba, the CEO of eHarmony, said in a statement that his company has made the types of practices laid out in the agreement a part of its business "for many years."
But Verba, and the heads of the other two companies, said they were eager to set an example for the rest of the industry.