Basics · Lesson 10 of 12 · 2 min read

Castling, En Passant and Promotion Explained

By · Updated 14 November 2026

Chess has three special moves: castling, which moves the king and a rook at once; en passant, a special pawn capture; and promotion, which turns a pawn into a new piece.

Try it in 3D

Castling

a8b7c6d5e4f3g2h1
Kingside castling: the king moves to g1 and the rook jumps to f1.

To castle, move the king two squares towards a rook; the rook then jumps over the king to the square next to it. Castling on the king's side is written O-O, on the queen's side O-O-O.

You may castle only if neither the king nor that rook has moved yet, all squares between them are empty, the king is not in check, and the king does not pass through or land on a square attacked by the opponent. Castling tucks your king into safety and brings a rook towards the centre, so most strong players castle early.

En passant

a8b7c6d5e4f3g2h1
Black has just played d7 to d5. White can capture en passant on d6.

If a pawn advances two squares from its starting square and lands directly beside one of your pawns, your pawn may capture it as if it had moved only one square. Your pawn moves diagonally to the square the enemy pawn passed over, and the enemy pawn is removed.

For White this can only happen with a pawn on the fifth rank; for Black, on the fourth. The right to capture en passant lasts for one move only: if you do not use it immediately, it is gone.

Promotion

a8b7c6d5e4f3g2h1
The pawn on e7 promotes as soon as it reaches e8.

When a pawn reaches the last rank it must be exchanged for a queen, rook, bishop or knight of the same colour. You can choose any of them, regardless of what pieces you already have, so having two or more queens is possible.

A queen is almost always the best choice. Choosing another piece, called underpromotion, occasionally avoids stalemate or delivers an immediate knight check.

Interactive lesson

Practise special moves on a 3D board

Pawnorama walks you through this lesson step by step. You make every move yourself, with hints when you need them. Free, no account needed.

Start the lesson

Common questions

Can you castle if your rook is attacked?

Yes. The restrictions are only about the king: he cannot be in check, pass through an attacked square, or land on one.

Is en passant optional?

Yes. It is never forced unless it is your only legal move, and it must be played immediately or the chance is lost.

Can a pawn promote to a king?

No. A pawn can become a queen, rook, bishop or knight, but not a king or another pawn.