"State action" is a term used to describe claims arising under the due process clause of the Fourteenth Amendment and the Civil Rights Act for which a private party is seeking damages because the state has violated that party's civil rights. Cases are summarized illustrating the doctrine's evolution over the past century. The 1875 Civil Rights Act provided the public-private basis for judicial rulings for at least the next 60 years. The state action doctrine gradually underwent a period of expansion from the formal public-private dichotomy to a functional analysis, from the late 1940's to the late 1960's. The public function (public sphere) doctrine made its first appearance in 1946. The 1960's saw a proliferation of state action cases and the degree of state involvement was utilized as the standard for determining state action. A major contraction of the state action doctrine and a revival of the public-private sphere began in 1972 with the first of three decisions authored by Justice William Rehnquist called the "Rehnquist Trilogy." Private education institutions have remained relatively immune from Fourteenth Amendment restrictions at the Supreme Court level but have been held more accountable in lower court rulings. The state action doctrine, after 100 years of transition, remains a difficult legal tool for the courts to define and administer. (MLF)