Cavallari also stated that when she joined The Hills, "It's work! I think that's why they're bringing me in, because I know what works".Lo and Audrina throw Lauren a surprise party, and Heidi shows up uninvited.

Kimberly Brandon and Chiara Kramer are shown as Montag and Patridge's respective co-workers and friends.

After Kristin Cavallari became the series' focal point in the second half of the season, the dynamic between cast members was adjusted in response to Conrad's absence.

The mid-season finale saw Conrad attend the wedding and reconcile with Montag before making her final appearance on the series.

During Part II, Conrad was replaced by fellow former Laguna Beach: The Real Orange County cast member Kristin Cavallari, whose interest in Justin Brescia resulted in a feud with Patridge.

The season was filmed primarily in Los Angeles, California, with additional footage in Crested Butte, Colorado, Oahu, Hawaii, and Las Vegas, Nevada. The Hills focuses on the lives of Lauren Conrad, Audrina Patridge, and Heidi Montag.

During Part I, Montag and her boyfriend Spencer Pratt nearly ended their turbulent relationship before deciding to marry.Despite widespread rumors that Conrad wished to leave the series upon the conclusion of the fourth season, producers persuaded her to film ten additional episodes in the beginning of the fifth season to close her storylines.After Cavallari was announced as her replacement, ten additional episodes were ordered to the season.She becomes involved in a feud with Audrina Patridge after beginning a relationship with her ex-boyfriend Justin Brescia.During the fifth season, Lauren Conrad serves as the series' narrator and focal point.Montag becomes dismayed after learning that Pratt has begun a flirtatious relationship with a local bartender Stacie Hall.