According to records at the University of Illinois at Chicago Library "The Cook County Socialist Party was founded in 1896 as a response to the Pullman strike in Chicago. It held its first convention two years later. In 1901 it joined with other socialists parties in the state to form the Socialist Party of Illinois. The state party affiliated with the national party and its leader Eugene Debs and grew in membership throughout the first two decades of the twentieth century but declined after World War One."
In 2005 the CSP's charter was suspended due to several officers not paying their dues and who later left the Party. The charter was later reinstated once a functioning Local Executive Committee of members in good standing was elected.