JA, Ja, or ja can mean:

• Jackass (for example, the television series)
• Jane's Addiction
• Japanese language (ISO 639-1 alpha-2)
• Yes, in Danish, Norwegian, Dutch, Afrikaans, German, Swedish, Slovene and Faroese
• I, in Croatian
• Judge Advocate
• Junior Achievement
• Jedi Academy
• Just asking
• And, in Finnish