Bradstreet was heavily involved in colonial politics. When the council met for the first time in Boston, Bradstreet was selected to serve as colonial secretary, a post he would hold until 1644. He was politically moderate, arguing against legislation and judicial decisions punishing people for speaking out against the governing magistrates. Bradstreet was also outspoken in opposition to the witch hysteria that infested his home town of Salem, culminating in numerous trials in 1692.