Attorney Generalalso intends to look into whether the California State University, Stanislaus Foundation violated public disclosure laws.
"This is not about Sarah Palin," Brown said in a prepared statement. "The issues are public disclosure and financial accountability in organizations embedded in state-run universities."
Matt Swanson, president of the foundation board, did not immediately respond to an e-mail seeking comment about the investigation.
Palin is scheduled to speak at a June 25 gala hosted by the foundation to mark the university's 50th anniversary.
Jason Recher, a spokesman for Palin, did not immediately return a call seeking comment.
The investigation came after students at the school retrieved five pages of the contract with Palin last week from a campus trash bin after hearing administrators might be shredding it.
State Sen. Leland Yee, a Democrat who has been seeking details of Palin's compensation package for several weeks, released copies of the paperwork earlier in the day.
Among the perks laid out in the contract, the former Alaska governor will fly first class from Anchorage to California - if she flies commercial. If not, "the private aircraft MUST BE a Lear 60 or larger ..." the contract specifies.
Palin also must be provided with a suite and two single rooms in a deluxe hotel near the campus in Turlock in the Central Valley. During her speech, her lectern must be stocked with two water bottles and bendable straws.
The document, dated March 16, does not include compensation details for Palin, who commands speaking fees as high as $100,000. Her appearance at the university gala is expected to draw a large crowd, with tickets selling for $500 each.
Palin's fee and accommodations will be covered entirely by private donations, not state funds, Swanson said earlier in the day.
The students who found the document said they acted on a tip that documents were being shredded when campus staff members were supposed to be on furlough.
"I was informed that there was suspicious activity taking place at the administration building, which I found very alarming," said 23-year-old Ashli Briggs, a junior at the school.
Briggs contacted senior Alicia Lewis, 26, who went with several other students to investigate. The building was locked and gated, but the students were able to retrieve piles of paperwork, including the contract document, from a nearby trash bin, Lewis said.
On Tuesday, Briggs and Lewis gave Brown's office material they said came from the trash bins, including two boxes of documents and two trash bags filled with shredded files.
The contract pages have Washington Speakers Bureau printed at the top and a contract number. The speakers bureau did not immediately respond to a request for comment.
Yee called the incident "a dark day for the CSU."
"This is our little Watergate in the state of California," he said Tuesday at a news conference where he was joined by Briggs and Lewis.
Russell Giambelluca, the university's vice president of business and finance, said no one at the university was advised to destroy specific foundation documents, and staff members routinely shred and dispose of paperwork that is no longer needed.
The CSU Stanislaus Foundation previously denied the AP's request to release details of Palin's contract under the California Public Records Act.
Last week, the university responded to a similar public records request by Yee by saying it did not have any documents related to Palin's appearance and had referred the matter to Swanson.
The next day, Swanson sent letters to both Yee and the AP stating that Palin's contract includes a strict nondisclosure clause. University foundations and other auxiliary organizations were not subject to the same public records requirements as the university itself, he said.
"At this point, we believe it's within our legal right to keep that information to ourselves," Swanson said before Brown's announcement. He called the latest dust-up "a little bit ridiculous."