Call it the “My Big Fat Greek Wedding” effect: Having lots of guests at your wedding is linked to a high-quality marriage, say researchers, who note that it’s not the lavishness of a wedding that matters but the size of the social network of friends and family who come to support the union.

The bulk of the new study, being released Tuesday by the National Marriage Project, also looks at how premarital sexual activities, cohabiting and childbearing may promote or hinder subsequent marital happiness.

Having multiple premarital sexual partners, cohabiting casually and “sliding” into marriage — instead of “deciding” to marry — were all associated with lower marital quality.