It took two to put together, but it seems very sturdy.  I was worried about breaking the slats because they don't lie perfectly flat after they're added to the bed. However, we put the mattress on and heard no snapping. I suggest letting the slats bow in the center as you are attaching the sides. You really can't keep them perfectly flat and attach them. It just won't work. They are pretty flexible. The bed seems very sturdy, and it's lovely. My 9 year old daughter loves it, but it's grown up enough for an adult bed too.