Membership in Mystery Writers of America numbers more than 3,000 Active, Associate, and Affiliate members internationally.

There are four categories of membership:

  1. Active members are published professional writers of fiction or nonfiction in the crime/mystery/suspense field.
  2. Associate members are professionals in allied fields such as editors, publishers, agents, booksellers, librarians, etc.
  3. Affiliate members are writers of crime/mystery/suspense fiction who are not yet professionally published, and others with an interest in the genre, including unpaid reviewers and fans or publishers not approved by MWA.
  4. Corresponding members are those who are qualified members living outside the United States.

You can find more information on the MWA Website:
general information | application form