This study analyzed the factors influencing motivation and persistence in pursuing and remaining in natural science careers among graduates of a laboratory school in Puerto Rico. A mixed-methods approach was employed, integrating an educational practice rating scale and open-ended questions, applied to a sample of 61 participants. A non-probabilistic convenience sampling was used. Quantitative analysis, through Friedman and Nemenyi non-parametric tests, showed significant differences in the evaluation of educational practices, highlighting laboratory experiences and exposure to the scientific community as those with the highest perceived influence on the motivation to pursue natural science careers. Complementarily, qualitative thematic analysis identified four emerging categories: early exposure to science, real-life application of content, vocational redirection, and limited institutio...