Which J.K. Rowling book was her first published work for adults?

The Casual Vacancy was J.K. Rowling’s first published novel for adults.

Published in 2012, the novel is a standalone work about a fictional English parish called Pagford. Its story begins after the sudden death of Barry Fairbrother, a parish councillor, creates a vacant seat and exposes conflicts over class, poverty, local politics, and social responsibility.

The book marked a major change from the Harry Potter fantasy series. It was written for adults and uses contemporary realism rather than magic. Its publication attracted enormous attention because it was Rowling’s first novel after Harry Potter and the Deathly Hallows.

The Casual Vacancy is distinct from Rowling’s later crime fiction. The Cuckoo’s Calling, published in 2013 under Robert Galbraith, was her first Cormoran Strike novel, while The Casual Vacancy is a separate ensemble novel.