What screw length do you use for 3/4 plywood walls?

[phil harold]

Make sure you have at least 1" of thread in wood
dont have much more than that you dont want to hit wires or pipes in the wall

if the studs or ply is bowed screws may not pull the sheet tight with less than an inch bite

[Ole Anderson]

I would just use part of my stash of 500 1-3/8" Kreg washer head pocket hole screws with the coarse threads, might be a bit short however. Using up my third of a bucket of 2-1/2" deck screws would be overkill for the reasons mentioned. Or if I got lazy I might use my 15 ga finish nailer with 2" galvanized nails, probably my best choice...