Chelsea wants to build some birdhouses. She has a 12 foot board of wood. Each birdhouse needs 3/4 foot of wood. How many birdhouses can Chelsea build?

To find the number of birdhouses Chelsea can build, divide the total length of wood by the length needed for each birdhouse: 12 feet / (3/4) foot/birdhouse = <<12/(3/4)=16>>16 birdhouses. Answer: \boxed{16}.