An electrochromic window assembly (10) is disclosed that includes a first substrate (12) and a second substrate (14) that is maintained in a parallel and spaced relation from the first substrate by means of a window frame (16) and spacer (18). The window assembly further includes an electrochromic device (22) mounted in the airtight chamber formed between the first and second substrates. Electrochromic device (22) may be mounted so as to provide an air chamber between first substrate (12), which is the external substrate, and electrochromic device (22). At least one of the chambers formed between substrates (12) and (14) and electrochromic device (22) may be filled with an insulating gas such as argon. Also disclosed are novel methods for manufacture of an electrochromic device for incorporation into such a window assembly. A novel electrochromic device is also disclosed having electrical bus clips (40a, 40b) secured about the entire periphery of the electrochromic device. Also disclosed is the use of steel bus clips for the electrochromic device.