To examine the role of integration in pattern masking, possible disruptive effects of integration were minimized by using a mask that overlaid completely all targets. Exposure durations were 10 ms, so under energy summation the target area was much darker than the rest. In another condition the mask was red and targets were blue, so under energy summation the target area could also be distinguished by hue. Masking magnitude increased with delay of mask onset, and it was established by four independent criteria that integration was negligible in the condition which produced most masking. It is deduced that integration is not necessary for masking; furthermore it is suggested that integration never produces masking, but rather may or may not protect from a disruptive effect of interruption. The argument is that were the visual system to have better visual resolution, it would suffer more given the same masking parameters. It is argued that type B masking functions arise from a combination of the facilitatory effect of integration and the detrimental effect of interruption.