The study protocol is designed to evaluate the effects of granting independent authorization for medical procedures to nurse practitioners and physician assistants on processes and outcomes of health care. Recent (temporarily) enacted legislation in Dutch health care authorizes nurse practitioners and physician assistants to indicate and perform specified medical procedures, i.e. catheterization, cardioversion, defibrillation, endoscopy, injection, puncture, prescribing and simple surgical procedures, independently. Formerly, these procedures were exclusively reserved to physicians, dentists and midwives. A triangulation mixed method design is used to collect quantitative (surveys) and qualitative (interviews) data. Outcomes are selected from evidence-based frameworks and models for assessing the impact of advanced nursing on quality of health care. Data are collected in various manners. Surveys are structured around the domains: (i) quality of care; (ii) costs; (iii) healthcare resource use; and (iv) patient centredness. Focus group and expert interviews aim to ascertain facilitators and barriers to the implementation process. Data are collected before the amendment of the law, 1 and 2·5 years thereafter. Groups of patients, nurse practitioners, physician assistants, supervising physicians and policy makers all participate in this national study. The study is supported by a grant from the Dutch Ministry of Health, Welfare and Sport in March 2011. Research Ethics Committee approval was obtained in July 2011. This study will provide information about the effects of granting independent authorization for medical procedures to nurse practitioners and physician assistants on processes and outcomes of health care. Study findings aim to support policy makers and other stakeholders in making related decisions. The study design enables a cross-national comparative analysis.