<p>This study aims to analyze the determinants of the probability of reaching high levels of human capital accumulation in OECD countries from 2000 to 2019. This research adopts an explanatory quantitative design based on a probabilistic panel analysis with data from 12 OECD countries between 2000 and 2019. The methodology follows a panel data approach during the period 2000 and 2019. For this purpose, variables related to human capital accumulation, productivity, healthcare system quality, educational expenditure, labor demand, labor quality, economic performance, mental health, and healthcare quality were systematically compiled. The results confirm that education and quality healthcare are fundamental to achieving high human capital, but their effects weaken in contexts lacking institutional stability and skill development initiatives. Improving labor income and healthcare quality jointly increases the probability of experiencing high human capital, while reliance on precarious employment and insufficient training hinder this. Additionally, total factor productivity, without appropriate redistribution policies, reduces the likelihood of raising human capital. Our findings place countries into three probabilistic trajectories: stable economies with diversified markets and robust systems (Canada, Switzerland); reform-driven progress (Poland, Turkey); and volatile economies facing inequality and institutional instability (Colombia, Mexico). This research is pioneering in identifying concrete probabilistic trajectories of human capital for twelve OECD countries, providing a nuanced understanding of how structural and institutional factors shape development paths. It offers novel insights into regional differences and the dynamic nature of human capital accumulation over two decades.</p>