Official ruleBase game, 6th edition (2025) and 5th edition
Can you play a development card the turn you buy it in Catan?
NoShort answer
No. You can't play a development card on the turn you built it. The exception is Victory Point cards: you can reveal any number of them, even ones built this turn, if they bring you to 10 points.
The rule
- Not on the turn you build it. A card bought this turn waits until a later turn.
- One per turn. You can play only 1 development card per turn.
- Any time in your turn. Before you roll the dice, or at any point in your Action phase. Playing a Knight before rolling can move the robber off your hex first.
- Victory Point cards stay hidden. Reveal them when they bring you to 10 points, including cards built this turn.
Example
Mia builds a development card and draws a Knight. She can't use it to move the robber this turn. On her next turn she can play it, even before rolling.
Why players argue about it
The timing rules are easy to forget: one development card per turn, and you can play it at any point in your turn, including before the dice.