As Zack and Kelly make plans for their wedding, they get a surprise visit from their old friend, Lisa Turtle. However, since Alex and Lesley also want to be Kelly's maid of honor, the competition between the three of them ensues. Meanwhile, Slater doesn't approve of Zack's decision and turns down his offer of being the best man. Screech agrees to take his place with predictable consequences.
Just as Zack and Kelly are getting pretty close, Kelly is accepted to the Semester on the Sea program, which involves a three-month cruise. Zack doesn't want Kelly to go, but she feels it's an opportunity she can't pass up. Zack tries to get accepted into the program as well, but none of his schemes work. He tries to get Screech to quit the program by scaring him, but that backfires and Zack impulsively makes an important decision. Meanwhile, Slater feels guilty when he sees another girl behind Alex's back and gets confronted by Leslie.
The gang is shocked by the death of a popular professor. As a result, Zack adopts a new attitude towards life by seizing the day and taking more risks.
With Kelly still pining over Professor Lasky, Zack tries to find ways of getting her attention and ends up volunteering as an orderly at the health center. Unfortunately, Professor Lasky winds up there as well, and Zack has to come up with one scheme after another to get him out of the way. Meanwhile, Screech tries to fit in with a group of pledges at his fraternity.
With Mike gone and in need of money for a trip to Cancun, Zack and the gang stage a rave in the dorm.
After a new professor takes over their Ethics class, the gang faces a dilemma when Zack gets his hands on a copy of the midterm. Meanwhile, Screech covers for Slater at the student union, but soon finds out that bussing tables isn't his forte.
A jealous Zack strikes back at Kelly and Professor Lasky with a vengeance by spreading the word about their affair, which climaxes at a costume ball. Meanwhile, Rogers gives the rest of the gang papers to fill out on a perfect mate profile for a psychology project, and Screech ends up getting the same mark as Alex.
While Screech hides a lab monkey destined for the zoo, Zack discovers Kelly's crush on Professor Lasky.
After car trouble intervenes with their Thanksgiving plans, the gang helps Mike, Leslie, and Screech prepare Thanksgiving dinner for a group of underprivileged kids.
While working at the Student Health Center Kelly realizes that she'd like to become a doctor, however, Zack discourages her arguing that it would require a lot of effort. After Kelly gets an extra job as a cocktail waitress, she starts to reconsider her choice of studying medicine in favor of taking the easy route and earning quick money from tips. Meanwhile, the guys help Mike prepare for his tryout for a comeback to the NFL.
Zack gets Screech to tutor a tennis star he is dating, only to find an attraction developing between the two of them. After they two argue, Screech temporarily moves in with Mike and drives him crazy. Meanwhile, Kelly and Leslie decide to throw a fancy college party, but things don't go quite as planned.
While the girls put together a male pinup calendar in order to buy a big screen TV, Zack poses as Lasky in order to date an admirer of the professor's.
Zack, Slater, and Screech make plans for a Friday night poker game. Mike nixes the idea of having the game and the guys decide to help him with his love life to get Mike off their backs. They encourage Mike to ask out the English literature professor, Judith Trudell, that he has a crush on. Meanwhile, Kelly, Leslie, and Alex develop a crush on their new karate instructor, John Hammer, and vie with each other to try to win his affections.
It's homecoming weekend. Leslie's parents come to visit her. She is sick of their controlling ways, so she asks Screech to be her date in order to freak them out a bit and Screech agrees to be especially geeky for this event. Meanwhile, Zack is invited to a homecoming banquet by the guest of honor, a football star who could help him score in some business. Also Alex and Slater become closer while training for the role of the university mascot.
Zack wants to take Leslie on a ski trip, however, she won't go alone with just Zack. Zack asks Slater to go along, but he must first find a date willing to go skiing with them. Slater meets a student activist who challenges him to embrace his Hispanic heritage. This topic causes friction between Zack and Slater, and puts the whole ski trip in jeopardy.
Slater is being courted by an exclusive fraternity while Leslie is being courted by a sorority. Zack really wants to get into the same fraternity as Slater, but they don't seem as interested in him. Zack manages to impress Rick the fraternity guy, but both he and Slater worry that Screech might ruin their chances in being accepted because of his goofiness.
Zack gets off on the wrong foot with his new professor of anthropology, Professor Jeremiah Lasky. Professor Lasky pegs Zack as a smart mouth immediately and turns the tables on him by selling him a copy of the midterm before Zack realizes that he is the instructor. All the girls have crushes on Professor Lasky, while Slater is trying to gain weight so that he can wrestle in a higher weight class.
Zack's pursuit of his suitemate Leslie is complicated by the arrival of a new transfer student -- his old high school girlfriend, Kelly.
Zach, Slater, and Screech start school at Cal U, where they find the adjustment to college life is harder than they expected.
