The Bechdel-Wallace test or Mo Movie Measure (often simply Bechdel test) is a media test which was developed by Liz Wallace and became widely known after Alison Bechdel featured it in her comic Dykes to Watch Out For, where the character Mo explains that she refuses to watch any film that doesn't fulfil this short set of conditions:
- the movie [media] has at least two women characters;
- who talk to each other;
- about something other than a man.
Passing the test shows only a very rudimentary level of female agency and independence in a work and cannot be construed any sort of guarantee of feminist, or even rounded, characterisation.
A failure may be indicative of the problems of token women characters. Failure of a work that passes some other, stricter media tests of female presence (such as the Mako Mori test or the Sexy Lamp test), is usually due to lack of female characters altogether, and sometimes due to male-satelliting roles and depictions of what female characters do exist.
The point of the Bechdel test is not whether individual works pass or fail, but what the trend over major masses of media are. A vast amount of geeky media fails the test.
Others have proposed corollaries to the test:
- One often used variation requires that the women are named characters.
- Anita Sarkeesian of Feminist Frequency added: "4. Do the female characters talk to each other about something other than a man for more than sixty seconds?"
- Tumblr user oranges8hands added "Both women have to be alive at the end too."
The test has been applied to various media:
- tigtog applied it to a list of the “Most Significant SF & Fantasy Books of the Last 50 Years”, with few books meeting the full criteria at Larvatus Prodeo
- The Dollar-And-Cents Case Against Hollywood’s Exclusion of Women on FiveThirtyEight.com, on budgets and profits of Hollywood films per Bechdel Test result
- TV Tropes has the Deggans Rule
- Latoya Peterson has some drafts of a race version of the Bechdel test: racialicious.com
- Alaya Dawn Johnson posted the literal race version of the test and applied it to science fiction at The Angry Black Woman
- Ars Marginal posted a version that required: "a movie must have: at least one named character of color, whose primary trait is not their race, who does something important besides help a White person." 
- Lauredhel made a variant for children's toys, regarding whether there were two girls depicted in an advertisement and whether they were playing at being stereotypical women or not at Hoyden About Town
- Randall Munroe analyzed how many popular recent films had two female leads. Fugitivus analyzed the response to his post.
- DTWOF: The Blog: The Rule explaining the history of the rule and displaying the original comic.
- Dykes to Watch Out For on Wikipedia
- Five ThirtyEight.com finds that movies that pass the Bechdel test do better in the box office.