Book ran unopposed for the 32nd district seat in the
Florida Senate in 2016. In the 2017 session, Book filed a bill that would remove
Confederate Memorial Day, celebrated on April 26, 2017, from Florida's list of 21 legal holidays. Her bill would also remove the birthdays of
Robert E. Lee and
Jefferson Davis as official state holidays. Book told CBS4, "during a time when the country is completely divided, I think we look at celebrating our unique coming together instead of some of the things that kind of create hate and divisive environments." On July 22, 2019, Book wrote Florida governor
Ron DeSantis a letter requesting a probe into how the
Palm Beach County Sheriff's Office handled a work release program for
Jeffrey Epstein. Following her request, Book reported that she began receiving calls from political supporters of Palm Beach County Sheriff
Ric Bradshaw, asking her to drop the request for an inquiry.
The Miami Herald reported that Book also received multiple anonymous calls and texts with more ominous demands to halt her request for a probe. Book voted against the controversial
Florida Senate Bill 86, which would have changed the implementation and administration of the
Bright Futures Scholarship Program. After the Democrats' incoming Senate leader for 2022–24,
Bobby Powell, decided to run for Congress, the Democratic caucus unanimously chose Book to be its leader for the 2022–24 legislature. A week later, on April 28, 2021, the Democratic caucus chose Book to serve immediately as minority leader, following a
no-confidence vote in then-leader
Gary Farmer. In 2022, Book faced a primary challenger, former Broward County Mayor
Barbara Sharief. The race devolved into a bitter battle between the two candidates, and Book's absenteeism from her district was made an issue by the Sharief campaign. Book ultimately won her primary, after being endorsed by Broward County Commissioner
Steven A. Geller, the Sierra Club, the
South Florida Sun Sentinel, the Florida Education Association, Pembroke Pines Democratic Club President Lourdes Diaz and Democratic activist Charles Horowitz. Notably, the ''Sentinel's'' endorsement was made with "little enthusiasm" because of the nastiness of the race. The bill would ban abortions after six weeks. This amendment eventually passed by
a ballot measure in 2024, and is in the Florida state constitution. ==Personal life==