Nursing specialization is considered a significant professional requirement to meet the challenges and needs of the health systems under evolving epidemiological patterns and scientific, technological, and social advances. In Spain, experiences in the training of specialist nurses have followed the same pattern and have been consolidated through legislation. This study aimed to analyze the implementation of the Spanish Nursing Specialty process according to the Royal Decree 450/2005. It used the documentary and systematic analysis method: a systematic review of official regulation documents published in the State Official Bulletin of Spain, Spanish legislative and historical nursing inventories, and other nursing-specific literature. This study shows an extensive account of nursing specialties' development process through a rather long period in Spain. It evidences the complexity involved to ensure legislative legality. The study also points to the need for homogeneity within the programs across the national territory and legal definition for specialty practice. This study could be an illustration to stimulate other nurse leaders in the world working in regulation and nursing specialty development to empower nurses' development and enhance the nurse specialists' contribution to archive the needs of the health system and healthcare of the population. HIGHLIGHTS:.