Minecraft wiki entry for Legacy_village_mechanics, associated text: Finding zombie villagers in the first place shouldn't be all that difficult. About every 20th zombie is a villager zombie, so it shouldn't take you too long to find two of them you can cure back into villagers and get the population booming by more..."natural" means. Additionally, when a villager is attacked by a zombie (any zombie) there is a chance (50% on normal difficulty, and 100% on hard) that they turn into a villager zombie instead of just being killed. There are also baby villager zombies, which are harder to trap, but can also be cured.