D0 mixing at CLEO II

The CLEO collaboration reported the observation of the ``wrong sign'' decay D0 -> K+ pi- in 1993. Recent upgrades to the CLEO detector, including the installation of a silicon vertex detector, have increased the sensitivity of the detector to D0 -> K+ pi-. Using 5.6 fb-1 of data we report a preliminary measurement of the rate of the wrong sign decay D0 -> K+ pi-, to be BR(D0 -> K+ pi-)/BR(D0 -> K- pi+) = (0.31 +/- 0.09 +/- 0.07)%. Additionally, combining this measurement with D0 proper lifetime information we set a limit on D0 - D0bar mixing of BR(D0 -> D0bar -> K+ pi-)/BR(D0 -> K- pi+) < 1.1% @ 90% confidence limit.