Harry Potter and the Methods of Rationality (HPMOR) is a novel-length fanfiction of Harry Potter (a.k.a. the canon) written by Eliezer Yudkowsky (originally under the pen name Less Wrong).

The story is set in an alternate universe from the one written by J.K. Rowling, where Petunia Evans married an Oxford professor of biochemistry, Michael Verres, instead of Vernon Dursley. Harry was introduced to science and rationality at an early age, and was allowed and encouraged to read on a wide range of topics including both fictional and non-fictional.

The story was first published on on 2/28/2010. The 122th and last chapter was published on March 14th, 2015. There is a mirror site at containing chapters and author's note, fan art, information on science and rationality, and a sign-up section for update notifications. The site also contains links to the story in other formats such as podcasts, iTunes podcasts, and bookstyle format for PDF, EPUB and MOBI. There are also links to discussion in the reviews section at, at TVTropes, and at the Less Wrong site.

Chapters and sub-booksEdit

HPMOR fingers cover

Cover for the HPMOR PDF available on

HPMOR has 122 chapters that were published between 2010-02-28 and 2015-03-14. They are usually named after the science involved in them.

The chapters were split after the fact into 6 sub-books :

  1. HJPEV and the Methods of Rationality (Ch. 1-20)
  2. HJPEV and the Professor's Games (Ch. 21-37)
  3. HJPEV and the Shadows of Death (Ch. 38-63)
  4. HJG and the Phoenix's Call (Ch. 64-85)
  5. HJPEV and the Last Enemy (Ch.86-99)
  6. HJPEV and the Philosopher's Stone (Ch. 100-122)

See Category:Chapters for articles on individual chapters and Explicit chapter titles for a list of alternate, more explanatory chapter titles for easy browsing.


HPMOR inspired many subfanfictions, i.e., fanfictions of the fanfiction. Some of them were written before HPMOR was completed and diverge from it; others were written since then.

Two subfanfictions are covered on this wiki in addition to HPMOR itself:

Read HPMOR Wiki:Subfanfictions if you want to contribute to subfanfiction pages.


For words of God see Word of God. For author's notes see Category:Author's Notes.