We present a framework for developing laser weld schedules featuring circular oscillation in the beam trajectory designed to reduce keyhole induced porosity in aluminum welds.  Our approach focuses on minimizing the frequency of keyhole collapses during the welding process by stabilizing the keyhole with circular beam oscillation.  The approach is guided by the hypotheses that if the oscillation period is less than the characteristic time of keyhole collapse, the keyhole can remain stable.  The characteristic keyhole collapse time is governed by the melt density and surface tension, as well as the keyhole radius, which can be increased by utilizing a larger oscillation radius.  By eliminating keyhole collapse, the creation of vapor bubbles in the melt flow can be avoided, thus eliminating a major source for weld porosity.   To verify these hypotheses, experimental results from laser welding of 3 mm thick aluminum alloy (AA 5754) sheets are presented. The test results confirm that porosity is substantially reduced when the oscillation amplitudes are increased beyond predicted threshold values for different oscillation frequencies.  These findings help to elucidate a new mechanism for improving keyhole stability in laser welding processes via laser beam oscillation and provide a framework for developing improved laser weld schedules.