Israel suffers from a severe STEM teacher shortage. To mitigate it, two retraining projects were developed: one recruiting academic high-tech professionals and the other -- practical engineers. This study evaluated both projects by exploring stakeholders' perspectives and examining graduates' retention. Applying a mixed-methods case study design, interviews were conducted with 35 graduates, 21 programme leaders and 6 school principals. Short demographic surveys were answered by 584 academic professionals and 356 practical engineers, and another 57 practical engineers answered a longer evaluation survey. The study found retention rates of 78% for academic professionals and 62% for practical engineers. To improve retention, both cohorts need better preparation in pedagogy, stronger support at school, higher wages and efficient administrative care. To realise their potential contribution, professional autonomy and principal's support are necessary.