VAX, computing on the Unix platform became feasible for S. In late 1979, S2 was ported from GCOS to UNIX, which would become the new primary platform.

In 1980 the first version of S was distributed outside Bell Laboratories and in 1981 source versions were made available. S was distributed freely in academic circles, and became popular among academic statisticians. The research team at Bell Laboratories published two books in 1984: S: An Interactive Environment for Data Analysis