He served in the Legislative Assembly of Ontario from 1990 to 1999 representing the New Democratic Party in the downtown Toronto riding of Dovercourt.
As Education Minister, one of Silipo's first decisions was to restore national indicator achievement tests, which had previously been removed by his predecessor, Marion Boyd.
He was also an active promoter of "de-streaming" in an effort to stop the practice of "streaming" children of immigrant and working-class families into non-academic courses of study.
[1] Although Silipo supported the Rae government's austerity Social Contract legislation in 1993, he was generally regarded as one of the more left-leaning figures in the cabinet.
[3] He ran for the leadership of the NDP in 1996, but was unable to build a strong support base and finished fourth behind Howard Hampton, Frances Lankin and Peter Kormos.