ABC are the first three letters of the Latin alphabet. They may refer to:

• American Broadcasting Company, a private US broadcaster
• Australian Broadcasting Corporation, national publicly funded broadcaster of Australia
• ABC Radio, the former name of Cumulus Media Networks, an American radio network (formerly owned by the American Broadcasting Company)
• ABC (Swedish news programme), a regional news programme
• Asahi Broadcasting Corporation, a Japanese commercial television and radio station
• Associated Broadcasting Company, a Philippine television network
• Associated British Corporation, a former British film and television company
• ABC (newspaper), Spanish daily newspaper

Rational emotive behavior therapy (REBT), previously called rational therapy and rational emotive therapy, is a comprehensive, active-directive, philosophically and empirically based psychotherapy which focuses on resolving emotional and behavioral problems and disturbances and enabling people to lead happier and more fulfilling lives. REBT was created and developed by the American psychotherapist and psychologist Albert Ellis who was inspired by many of the teachings of Asian, Greek, Roman and modern philosophers. REBT is one form of cognitive behavior therapy (CBT) and was first expounded by Ellis in the mid-1950s; development continued until his death in 2007.