Minecraft wiki entry for Before_Village_%26_Pillage, associated text: You can reproduce/abuse this behavior by building 6 houses on the ground level (enough to set the villager limit to 2), drop 2 (or more) villagers into a 6 blocks deep hole, and leave one villager at the top to keep the houses "alive". The villagers in the hole will breed indefinitely, because they're not counted against the cap. As of Minecraft Java Edition 1.8, you need to make the villagers willing to breed, by also giving them food (or give them a farm, a crop, with a farmer), or trading with them.