Changing subnet mask

Hi,
My network currently uses the subnet mask 255.255.255.0 and IP range 1.0.0.1 – 1.0.0.254. I would like to switch the entire network over to subnet mask 255.255.0.0. Does this simply involve changing the TCPIP settings for all devices on the network (does this also include switches)? Is there anything else I need to do?