This paper introduces the underactuated part alignment system (UPAS) as a cost-effective and flexible approach to aligning parts in the vertical plane prior to an industrial robotic assembly task. The advantage of the UPAS is that it utilizes the degrees of freedom (DOFs) of a SCARA (selective compliant assembly robot arm) type robot in conjunction with an external fixed post to achieve the desired part alignment. Additionally, the UPAS is not constrained to work with rigid, polygonal parts. Three path planning techniques are presented that can be used with the UPAS to achieve the proper part rotation. The results from laboratory testing show that the UPAS can be used to consistently achieve the desired part rotation to within 0.5% of the desired value.