A MEMS device is packaged with a control material that is included in the package to affect an operation of a moveable element of the device. The control material may affect operational characteristics including actuation and release voltages and currents, mechanical affects including damping and stiffness, lifetime of the device, optical properties, thermal affects and corrosion. The control material may be inserted into the package as part of any of several structural components of the package or the MEMS device.