- ABCDEF stands for Advanced Bonewits’ Cult Danger Evaluation Frame (est. 1979)
- ABCDEF stands for American Boys Club for the Defense of Errol Flynn
- ABCDEF A Better Complete Development Engineering Firm (San Carlos, CA)
- ABCDEF stands for Abstinence, Be Faithful, Correct and Consistent Condom Use and Circumcision, Diaphragm for HIV Prevention, Exposure Prophylaxis, Female-Controlled Microbicides (approach to prevention of AIDS virus)
ABCDEF