Small molecule inhibitors of Stat3 and their derivatives are disclosed. Also described are methods to inhibit cell growth by use of Stat3 inhibitors, and the use of Stat3 inhibitors for the prevention and/or treatment of cancer. Further, inhibitors of Stat3 that also do not inhibit Statl are described as well as their derivatives. Methods of screening additional compounds for Stat3 inhibition activity and/or non-inhibition of Statl activity are also described herein.
