Rob Kampia is an American activist who is the co-founder of the Marijuana Policy Project (MPP), co-founder of Decriminalize Sex Work (DSW), and founder of the Marijuana Leadership Campaign.

In 1988 Rob Kampia was arrested for growing marijuana for personal possession while attending Penn State University and served three months in prison. This experience led him to become a marijuana legalization activist. In 1993, Kampia moved to Washington D.C. to work with NORML (National Organization for the Reform of Marijuana Laws). He then formed MPP with Chuck Thomas and Mike Kirshner "when his relationship with NORML director Richard Cowan soured."

He served as MPP's executive director from 1995 until 2017, when he stepped down amid increasing public scrutiny of men accused of sexual misconduct and harassment. After resigning from MPP, in 2018, Kampia founded the Marijuana Leadership Campaign and co-founded DSW. Kampia continues to be a director at both organizations. Kampia "came out" as a client of sex workers to the Washington Examiner in 2019, saying "It's important, like the gay rights movement. ... If everyone knows someone who is gay, maybe being gay shouldn't be a hassle or a crime," Kampia said. "With this, anyone who has been engaged in paid sex, on the provider or the client side, should speak up and out themselves. I just outed myself to a reporter for the first time here."

Kampia grew up in Harleysville, Pennsylvania, a small suburban town 30 miles (48 km) northwest of Philadelphia. Kampia was valedictorian of his 300-person graduating class at Souderton Area High School in 1986, served three months in prison from November 1989 to February 1990, for growing cannabis for personal use at Penn State University, and was elected student body president two years later at that same school. Three days after graduating with honors from Penn State in 1993 with a bachelor's degree in engineering science (a multidisciplinary honors program) and minor in English, he moved to Washington, D.C., for the purpose of ending the government's war on marijuana users.

Rob Kampia co-founded MPP in 1995. MPP has a lobbying branch, an educational branch, and a political action committee and is based in Washington, D.C. MPP employs approximately 40 staffers, as well as consultants to pass statewide ballot initiatives and lobbyists to pass legislation through state legislatures.

Kampia has been quoted in almost every major newspaper in the U.S., discussed the cannabis issue dozens of times on local and national radio, appeared on national TV more than a dozen times, and has testified before Congress on two occasions.

In August 2009, seven MPP staffers quit over an alleged incident of sexual misconduct by Kampia involving a female subordinate after an office happy hour. According to former employees, department heads at the organization unanimously asked Kampia to move into a different position than executive director over the incident. Following his statement that he was "hypersexualized," Kampia was "encouraged" by the MPP board of directors to take a three-month leave of absence and his return is subject to "convincing the board he has dealt with his issues." This reportedly resulted in a cancellation of the MPP's annual fundraiser at the Playboy Mansion, with MPP's acting director indicating that "the PR ramifications of holding the event right now are probably obvious." Kampia likened the incident to the Monica Lewinsky scandal, saying he could remain in charge just as Bill Clinton did.

In February 2018, "NCIA's Board of Directors voted to remove Rob Kampia in accordance with our bylaws after an ethics committee review surfaced a pattern of behavior unbecoming of a board member." Kampia labeled his ouster as a "coup" in an attempt to save face and spin some sort of public sympathy. This occurred soon after prominent NCIA board member Kayvan Khalatbari had resigned, in part, because the organization hadn't moved to reject Kampia sooner.