This study addresses the STEM workforce shortage by examining online STEM course withdrawals. This article categorizes withdrawal reasons using a two-tiered coding system based on a theoretical framework. Institutional data, analyzed through qualitative methods and descriptive statistics, showed withdrawal rates between 2.0-9.6%, with no significant differences between general education and degree support courses or STEM disciplines. External and environmental factors accounted for 49% of withdrawal reasons, followed by institutional characteristics (23%). These findings, especially regarding external and environmental factors, offer crucial insights for designing interventions to enhance online course persistence, bridging the STEM workforce gap.