Gov. Pat Quinn is expected to sign legislation later in the day that will make Illinois the 20th state to legalize medical marijuana.
His remarks Thursday at the University of Chicago will focus on providing relief to the seriously ill, including veterans.
The Chicago Democrat will also tout Illinois' strict standards, which experts say are among the nation's toughest.
The measure outlines a four-year pilot program that requires patients and caregivers to undergo background checks and sets provisions for state-regulated dispensaries. The proposal says patients can be allowed up to 2.5 ounces at a time.
Jim Champion is a veteran with multiple sclerosis. He'll be one of the speakers at the event.
Currently 19 other states and Washington D.C., allow medical marijuana.
The bill is HB1.