This study addresses the burgeoning phenomenon of fully online alternative teacher certification programs (ACPs). In Texas where most teachers are prepared via ACPs, our research zeroes in on the proportion of teachers who are prepared fully online and the relative effectiveness of teacher preparation programs on student achievement and teacher retention. Using statewide longitudinal data from 2014-2023, our findings show that 1 in 4 of Texas students are being taught by teachers prepared fully online Students taught by teachers prepared online exhibit comparable levels of achievement to those taught by uncertified teachers, underperforming compared to students taught by teachers from other preparation pathways. Moreover, these teachers exhibit a markedly higher turnover rate. This study contributes to the ongoing discourse on teacher preparation quality, offering insights for policymakers and stakeholders.