Doug's 1st Movie is a full-length movie based on the animated series, released on March 26, 1999. Voice actors and actresses from the main series reprise their respective character roles. Doug's 1st Movie was the only full-length film released in Doug's entire run. The plot of the movie takes place directly after the Disney's Doug 1999 series finale, Doug's Marriage Madness.
- Thomas McHugh as Doug Funnie, Quailman, Lincoln
- Fred Newman as Skeeter Valentine, Bud Dink, Porkchop, Ned Cauphee
- Chris Phillips as Roger Klotz, Boomer Bledsoe, Larry, Mr. Chiminy
- Constance Shulman as Patti Mayonnaise
- Frank Welker as Herman Melville
- Alice Playten as Beebe Bluff, Elmo
- Guy Hadley as Guy Graham
- Doug Preis as Phil Funnie, Bill Bluff, Willie White, Chalky Studebaker, Bluff Agent
- Becca Lish as Judy Funnie, Theda Funnie, Connie Benge
- Eddie Korbich as Al & Moo Sleech, Robocrusher
- David O'Brien as Quailman Announcer
- Doris Belack as Mayor Tippi Dink
- Greg Lee as Principal Robert "Bob" White
- Fran Brill as Mrs. Perigrew
The School Dance is coming up. Doug signs himself and Patti up to be the planners and Doug wanted to be with Patti.
Later that night, Doug and Skeeter discover a monster that lives in Lucky Duck Lake. At first they are scared of him, but they later on find him to be nice. They also discover the monster to be proof that Bill Bluff is polluting the lake which created the monster. The monster almost eats the book Moby Dick, but Skeeter stops him, saying, "Stop! You almost ate Herman Melville", and the monster responded, so they name him Herman Melville. They show it to Mrs. Dink, who's the mayor. She tells Doug and Skeeter not to tell anyone about Herman and the polluted lake or else Mr. Bluff will kill the story. Mrs. Dink tries to come up with a plan to make sure Mr. Bluff would not interfere. But all this commotion with the monster makes Doug forget that he was supposed to meet Patti at Mr. Swirly's. When he remembers this, he runs to Swirly's as fast as he can using the quickest shortcuts that he knows. Once he gets there, he doesn't see Patti. He asks Mr. Swirly if he's seen her, and he says that she was here for a while and looked very upset, and then left with a guy who kept talking about his big plans for a dance. When Doug heard this, he knew that this guy was no one else but Guy Graham, a snobby upper class man who wants Patti. Meanwhile, Roger and the AV nerds are building a robot to kidnap Herman, but when they build the robot it acts like Roger's babysitter.
Doug then rushes to the night club, where Guy and Patti are working on the dance. He apologizes to Patti there and she accepts his apology. But Guy cuts in and says that Doug is just a stupid little kid. Doug, very angry now, goes against Mrs. Dink's advisories, saying that he has proof that Bluff is polluting the lake. Guy then calls Doug a liar. Doug then invites them both to the report that is being held in front of Mr. Dink's house about Herman and the pollution. Doug then leaves, but the picture of Herman's foot falls out of his pocket without him knowing. Guy picks up the picture and realizes that Doug was telling the truth; he then calls Bluff, with whom he has connections to. The next day, Patti asked Doug to bring Guy. Doug allows it in hopes to get back at him; however, Doug is unaware that Guy already knows the truth about Herman. At the reporting, Doug sees that a news reporters camera is inflatable. He then realizes that the news company is a fake, that it is supporting Bill Bluff and trying to compensate the monster. Doug then has to tell everyone that there has been a mistake, Patti gets mad at him, thinks that he is a liar and walks away with Guy.
The next day, Doug disguise Herman as a school student. Everyone immediately takes a liking to Herman. Doug tries to talk to Patti; however, Patti refuses to talk to Doug, thinking Doug is lying to her again. Later that night, Doug blames Herman for ruining everything; however, Herman shows Doug that the lake is polluted and he can't come back. Suddenly, Bluff finds the boys with Herman and kidnaps the monster. Doug realizes that he was using Herman to impress Patti and he didn't think about Herman's safety. The next morning, Doug knows that this is his last chance to save Herman. He goes to the school newspaper room, hoping to find Guy who can lead him to Bluff. Guy isn't in the room, but Doug sees a newspaper article that says that Mr. Bluff and his men blast a monster at a school dance. Doug is saddened by the news and believes that Herman has died (Despite the fact that he said the paper was the paper for the next week), but he then realizes that the school dance isn't until tonight and this is what is being planned to happen so. Doug and Skeeter call Roger and The Sleech twins to help.
At the school dance, he is forced to choose between going after Patti or saving Herman. Doug eventually chose the latter and he & Skeeter took Herman to Crystal Lake. When they did that, Bluff catches the duo and starts to enslave them, but is stopped by Beebe who arrives to force her father off of the scene to defend her friends. Mrs. Dink later arrives to straighten this mess out too. Doug then finds Patti in front of the woods and Doug tries to tell her that he did tell the truth and that he is in love with her but is interrupted by Herman. With the return of Herman and a copy of the newspaper Patti sees that Doug had been telling her the truth all along and dumps Guy. Also Skeeter gives Herman the Moby Dick book for something to eat in the lake and Herman also gives Doug a flower to give to Porkchop to which Porkchop comes running out of the woods into Herman's arms. The kids say goodbye to Herman; after Herman jumps back into the lake, Doug tells Patti he likes her and Roger becomes friends with Doug, but is interrupted by the robot. Doug starts dancing with Patti and Skeeter dances with Beebe as the music continues in the background. It is said that Mr. Bluff is going to clean up the Lucky Duck Lake.
Doug closes his journal by saying he was worried about looking like a loser and he learns to do the right thing.
Doug's 1st Movie received negative reception from various critics. Robert Ebert rated the movie 1½/4 stars, stating "Doug's 1st Movie is a thin and less than thrilling feature-length version of a Saturday morning animated series, unseen by me."