Ashlee Simpson, Pete Wentz Wed in Calif.

May 18, 2008 — -- Ashlee Simpson and Pete Wentz are now reportedly man and wife.

The pop-star little sis of Jessica Simpson and the "Fall Out Boy" bassist wed Saturday in a private ceremony at the Encino, Calif., home of Ashlee's parents, according to People magazine.

The service had an "Alice in Wonderland" theme. Joe Simpson performed a non-denominational ceremony for his 23-year-old daughter and her 28-year-old groom, the magazine reported.

Ashlee's sister, Jessica, attended the event with Dallas Cowboys quarterback Tony Romo, though tabloids have claimed the pair split.

Ashlee's mother, Tina Simpson, was also among the 150 people who watched the pair get married.

The "Pieces of Me" singer donned an ivory lace wedding gown by Monique Lhuillier accessorized with a diamond necklace and earrings by Neil Lane, People magazine reported.

Pete's English bulldog, Hemingway, was the ring-bearer, and the reception featured a wedding cake by Sam Godfrey of Perfect Endings featuring a top hat, tea pot, stop watch and a pot of flowers on top, the magazine reported.

The paparazzi staked out the wedding location and began gathering before 3 p.m. White shuttle vans with deeply tinted windows were streaming through the gates, as were several delivery vehicles.

Drivers of a few expensive cars who arrived at the guard tower were told to park elsewhere and take a shuttle. One was a well-dressed woman who arrived in an Audi packed with red boxes.

The wedding followed an intimate rehearsal dinner Friday.

On Thursday, the Simpson women threw a bachelorette bash for the youngest member of their clan at Tina and Joe's home, according to E! News. Meanwhile, Pete skipped a raucous bachelor party to dine with his pals and his now-father-in-law at hot spot Mr. Chow in Beverly Hills.

Ashlee and Pete, who began dating in fall 2006, announced their engagement April 9. Tabloid reports, blog rumors and "baby bump" photos have fueled speculation that Ashlee is pregnant, but the couple has long denied its expecting a child.

The wedding may help generate more buzz for Ashlee's new album "Bittersweet World," which she released last month. The record peaked at No. 4 on the Billboard 200 in its first week and the tracks have logged more than 19 million plays on her MySpace page.

ABC News' Sheila Marikar and The Associated Press contributed to this report.