While Sheila was attending Catholic University in Washington D.C., she became involved in the Civil Rights movement, an experience that radicalized her politically, and led to a decades-long period of left-wing political work.

She participated in a series of demonstrations and other political activities in Cambridge, Maryland during the summer of 1963.

Around this time she also got involved with SNCC, the Student Non-Violent Coordinating Committee and later participated in the Mississippi Freedom Summer voting rights drive.