Education policy stakeholders attempt to counteract teacher shortages by recruiting persons from outside of the teacher career. However, teachers' job satisfaction, a key predictor for teacher retention, often differs between those originally trained as a teacher and those from different career pathways. Applying multiple indicator multiple causes (MIMIC) bifactor models on PISA data (N = 125,764 teachers), we found that first career teachers show higher job satisfaction. Furthermore, the curricular preparedness by initial education is more important for those, who always intended to become teachers when compared to those arriving from alternative routes. Based on findings in this study, we recommend improvements of alternative certification programs, working conditions, and professional development opportunities for persons who did not initially plan to become teachers to increase overall teachers' job satisfaction.