Yes, for a U.S. passport (and most international equivalents), you should include your full legal middle name as it appears on your evidence of citizenship (such as a birth certificate or naturalization certificate). The U.S. Department of State requires that the name on your passport application matches your legal ID exactly. While some people use only a middle initial in daily life, having the full name on your passport helps prevent identity confusion, especially since many people share the same first and last names. It is also crucial for international travel because many "Secure Flight" programs require that the name on your airline ticket matches the name on your passport exactly. If your passport has your full middle name but your ticket only has an initial, you may encounter extra scrutiny or delays at security checkpoints. If you have multiple middle names, all of them should be listed to ensure your travel document is a complete reflection of your legal identity.