"You know, house-elves get a very raw deal! It's slavery, that's what it is! That Mr. Crouch made her go up to the top of the stadium, and she was terrified, and he's got her bewitched so she can't even run when they start trampling tents! Why doesn't anyone do something about it?"
—Hermione begins her campaign for the better treatment of house-elves
Before her fourth year at Hogwarts, Hermione spent much of the summer holidays at the Burrow with Harry and Ron, sharing a room with Ginny Weasley. With the other Weasleys, they attended the 1994 Quidditch World Cup in August. After the game, the communal camp-site was set upon by Death Eaters. Hermione, Harry, and Ron fled into the woods and witnessed the casting of Morsmordre. Initially caught up in the chaos surrounding the effort to catch the caster, she took exception to the accusations levelled against Harry, and the many wizards' treatment of the house-elf Winky who had also been at the scene.
Once at Hogwarts, Hermione began a crusade for the liberation of house-elves by beginning the Society for the Promotion of Elfish Welfare, or what she and the group called S.P.E.W, (or as Ronald Weasley called it: spew) having been appalled by Bartemius Crouch's abusive treatment of his house-elf Winky.
Harry, Ron, and Neville Longbottom only reluctantly joined, mostly in order to prevent Hermione from nagging them about it. Hagrid as well as Fred and George Weasley refused to join on the grounds that it would upset the house-elves, though Fred did tell Hermione how to get into the Hogwarts kitchens, where she spoke to Dobby and Winky. Hermione considered the former to be a good example of a free elf, and tried to comfort the latter about being sacked by Crouch, but Winky soon became upset by Hermione's claims that house-elves deserved to have holidays and wages, along with the other elves.
After the events surrounding Harry's name coming out of the Goblet of Fire, Hermione was the only student who believed Harry's innocence; in fact, she "accepted his story without question." Even Ron was suspicious that Harry had cheated in order to gain more glory, creating a rift between the two for some time. Hermione helped Harry for the Triwizard Tournament by teaching him useful spells, such as Stupefy, Impedimenta and Accio and tried to get Harry and Ron to talk to one another multiple times.
At this time, Hermione unknowingly attracted the interest of Durmstrang Triwizard Champion and Bulgarian International Seeker, Viktor Krum for her intelligence, unconventional beauty, and the manner in which she declined to hound him for autographs, unlike other girls. Krum began following Hermione to the library and other places around Hogwarts, and even asked Harry if it was all right for him to pursue Hermione. He eventually asked her to attend the Yule Ball with him, and she accepted, not telling anyone but Ginny Weasley.
"It was Hermione. But it didn't look like Hermione at all. She had done something with her hair; it was no longer bushy but sleek and shiny, and twisted up into an elegant knot at the back of her head. She was wearing robes made of a floaty, periwinkle-blue material, and she was holding herself differently, somehow--or maybe it was merely the absence of the twenty or so books she usually had slung over her back. She was also smiling--rather nervously, it was true--but the reduction in the size of her front teeth was more noticeable than ever; Harry couldn't understand how he hadn't spotted it before."
—Description of Hermione at the Yule Ball
Thus, when the pair arrived, many were stunned and jealous. Hermione wore robes of "floaty, periwinkle-blue material," and her hair in an "elegant knot at the back of her head." The attention to her appearance was unusual, and she received many positive remarks on it. Hermione commented that she had used Sleekeazy's Hair Potion, but that it was too much work to use it every day. Upon seeing Hermione with Krum, Ron was overcome with jealousy. Hermione intended for Ron to ask her, but his invite was insensitive and at the last minute. The two rowed about it in the common room, in which Hermione revealed that he should have asked her instead of Krum, but Ron misunderstood the point. After that, the two were seemingly more polite, although Ron continued to show dislike of Krum.
Hermione was chosen as a "kidnap victim" for Krum during the Tournament's Second Task, something that she subsequently endured teasing over. She was taken to the bottom of the Black Lake to await rescue from Krum, who donned a half-shark Transfiguration. Krum managed to rescue her and carried her to the surface, where he revealed to her later that he "never felt this way about any other girl" and asked her to visit him in Bulgaria over the summer.
Ron: "She'll be after you next, Hermione."
Hermione: "Let her try! I'll show her! Silly little girl, am I? Oh, I'll get her back for this."
— Hermione and Ron discussing Rita Skeeter
Rita Skeeter, a journalist for the Daily Prophet and unregistered Animagus, was hiding in beetle form in Hermione's hair during this conversation. Hermione had previously told Skeeter off for printing horrible lies about Harry and Rubeus Hagrid, angering the journalist, who wrote a scathing article on "the devious Miss Granger," claiming that she was toying with both Harry and Krum's affections and possibly brewing Love Potions. In the words of Ron, Skeeter was making Hermione out to be a "Scarlet Woman." Although she called Hermione "plain" in the article, she had previously reported Hermione as Harry's "stunningly pretty... girlfriend" by likely twisting and sensationalising the words of Colin Creevey and thus used this as the basis for the article. Although Hermione found the lies ridiculous, some people believed them and started sending Hermione hate mail, and even Molly Weasley treated her coldly until Harry corrected her. Hermione found this irritating and vowed to get revenge on Skeeter for her libel, and she did.
On the ride home on the Hogwarts Express, Hermione happily revealed she uncovered Skeeter's status as an unregistered Animagus and had trapped her in a jar. She kept Skeeter from writing for a year by threatening to expose her to the authorities. She single-handed drove Skeeter into poverty, gaining revenge for the pain caused to Harry and her other friends. However, with the return of Lord Voldemort and the murder of Cedric Diggory at the end of the school year,there were much more serious challenges ahead for Hermione and her friends.