Chelsea was so determined to get Patrick for herself she drugged Patrick, and when that didn't seem to work, she spiked Billie Reed's drink at Alice's, not realizing it would drive Patrick and Billie into each other's arms.
Chelsea was terrified that Bo would turn her in, but Billie stepped up to take the blame.Bo found out that Chelsea has been driving the car and tried to protect her, but Hope was furious with Chelsea.Chelsea, Billie, and some of the other sorority sisters tried to take the information to the dean, but Ford Decker's dad was very good friends with the dean and no action was taken against Ford.Chelsea and her sorority sisters decided to teach Ford a lesson.Not long after they returned, Chelsea and Nick began dating.
Chelsea found out that Nick had a one night stand with Billie.
Upset over loosing Chelsea's friendship, Nick slept with Chelsea's mother, Billie.
To win favor back with Bo and Hope, Chelsea volunteered to take money to Belle, Shawn, and Claire who were hiding in Canada. On the trip, Nick and Chelsea's relationship turned flirtatious.
Chelsea schemed to keep Bo and Hope apart so that Hope would not convince her Bo to turn Chelsea in for Zach's accident.
Eventually, Chelsea did turn herself in for being responsible for the accident and she was given community service for her involvement in Zach's death.
Chelsea was conflicted over her feelings for Jett, but eventually returned back to Nick.