INTRODUCTION: In 2021, 741 people died due to occupational accidents in the construction sector in Europe (Eurostat, 2023). The European Commission developed the Strategic Framework for Health and Safety at Work 2021-2027, outlining objectives to improve the health and safety of workers. One of these objectives is to improve the safety training. METHOD: Focusing on this point and considering the safety training offered to construction workers in Spain, in the first hypothesis, we propose that more safety training reduces accidents by separating mandatory and voluntary training. In Hypothesis 2, we analyze whether voluntary training has a greater effect on reducing accidents than mandatory training. Finally, in Hypothesis 3, we test whether specific training is more effective than general training in reducing accidents. To test these hypotheses, we used data from training providers, accident data from the Labor Authority, and economic data from Informa & Bureau van Dijk (SABI). The final sample comprises data from 1,283 Spanish construction companies over 11 years (2007-2017). The methodology involved analyzing the relationship between training and accidents, addressing our variables' apparent endogeneity using instrumental variables. We analyzed the effect of accident training in the same year and, based on the learning curve theory, we also considered the previous three years of training. RESULTS: Contrary to our hypotheses, our results show that more hours of safety training of all types are associated with more accidents, questioning its effectiveness. This finding highlights the need for an in-depth analysis of the training process to identify areas for improvement. Finally, we provide a comprehensive analysis of the training processes within the Spanish construction sector and propose potential modifications aimed at improving it and, consequently, reducing accidents.