Pi Beta Alpha is a fictitious sorority in the Sweet Valley High book series.
The sorority is the most popular on the SVH campus, and because of the haughtiness of some of its members, also called the snobbiest. The male equivalent is Phi Epsilon, while not as snobby, was run by egocentric Bruce Patman.
Jessica Wakefield is the president of the sorority, and she, along with Lila Fowler and others of her friends, intend to keep it exclusive. Her most blatant attempt on this, was against junior Robin Wilson, who had the misfortune of being obese. Using some of the most cruel hazing tactics possible, they subsequently blackballed her. However, Jessica's twin sister, Liz, is good friends with Robin and did her best to get her accepted by the sorority. When that didn't work, Liz confronted Jessica for blackballing her. She defends her actions, stating that Robin's obesity was unacceptable for the sorority's image. However, Liz isn't convinced due to knowing how shallow and conniving Jessica is. She has threatened to expose her and Pi Beta Alpha for their actions against Robin in an article on The Oracle if they don't overturn their decision.
Later on, they relented, and overturned it, after Robin shed the weight, became a cheerleader and won Miss Sweet Valley High. She stunned them all by declining the membership. Robin remembered how Jessica and the others were rude to her with their cruel hazing and blackballing her when she was obese and found who her true friends are.
Although Jessica is the president, Liz isn't as involved with the sorority as she would like. Elizabeth and her friend, Enid Rollins are members in-name-only as neither want anything to do with the sorority seeing it for what it really is: elitist and self-centered.