Chachi has a hard time accepting the fact that his mother ( Ellen Travolta) is dating. Fonzie has bitter feelings toward Potsie when he is invited to supper with the Cunninghams and he himself is not asked.

Chachi suggests to Joanie that they should date other people; but with Chachi's jealousy, the idea backfires on him when Joanie makes a date with another guy at a classy restaurant. Chachi then coaxes Fonzie into visiting the restaurant with him so they can spy on Joanie and her date.

With Richie in the Army, Lori Beth calls on Fonzie to stand in as Richie's proxy when it is time to deliver her baby.

Fonzie and Roger date the same girl.

Fonzie fills in as a substitute teacher for Roger and inadvertently causes trouble for him by raising the issue of sex education.

Note: This episode marks the first appearance of Scott Bernstein as Melvin Belvin.

Jenny and Joanie end up in serious trouble when a sorority asks them to break the law and steal a statue from a local park in order to become members.

Special guest star: Phil Silvers (Cathy Silvers' father) as Mr. Piccalo, Jenny's father.

Note: Ed Peck returns in his recurring role of Officer Kirk, who busts Joanie and Jenny.

Fonzie has a serious relationship with a girl who has a secret—she's a nun.

Joanie babysits her new nephew when the household's heating system malfunctions.

Joanie and Chachi call on Fonzie to try to transform nerdy Eugene into a tough-as-nails fighter to impress Jenny.

Fonzie and Al travel to Alabama to participate in civil rights activities with the Freedom Riders in 1962.

Fonzie and Chachi visit their grandmother Nussbaum ( Frances Bay); but when they notice her acting abnormally, Fonzie and Chachi believe she is going senile. Worried about her living alone in that condition, Fonzie suggests that Grandma move into a retirement community, which does not sit too well with her.

When Frankie Avalon (who portrays himself as Al's distant cousin) informs Al that he would not be able to headline the Leopard Lodge's annual Poobah Doo Dah musical due to family issues, Al persuades Fonzie to impersonate him—which turns out to be a disaster. However, Avalon does show up at the last minute and performs his signature song " Venus" to an audience of swooning girls—including Jenny, who climbs onstage and wraps her arms around Avalon's leg, reluctant to let go.

Special guest star: Frankie Avalon as himself.

The gang works to give Fonzie the birthday present of his life—a face-to-face meeting with his hero, the Lone Ranger.

Joanie and Chachi collaborate on a song, Potsie wants to join the Leopard Lodge, and Marion gets the lead in a musical.

Roger's juvenile delinquent brother Flip ( Billy Warlock) comes to Milwaukee to straighten out his life.

Jealous of the attention Joanie had been giving to her new friend Mikki ( Crystal Bernard), Jenny spreads a vicious rumor that Fonzie had gotten Mikki in trouble.

Al seeks permission to marry Chachi's mother.

Note: This episode has two endings, one where Al and the Arcolas move to Chicago to set up the spinoff Joanie Loves Chachi; and the other, for syndication purposes, where they appear to stay in Milwaukee. This episode marks the final regular appearance of Al Molinaro as Alfred Delvecchio.