Patient safety has progressed in 15 years from being a relatively insignificant issue to a position high on the agenda for health care providers, managers and policymakers as well as the general public. Sweden has seen increased national, regional and local patient safety efforts since 2011 when a new patient safety law was introduced and a four-year financial incentive plan was launched to encourage county councils to carry out specified measures and meet certain patient safety related criteria. However, little is known about what structures and processes contribute to improved patient safety outcomes and how the context influences the results. The overall aim of this thesis was to generate knowledge for improved understanding and explanation of influences on patient safety in the county councils in Sweden. To address this issue, five studies were con-ducted: interviews with nurses and infection control practitioners, surveys to patient safety officers and a document analysis of patient safety reports. Patient safety officers are healthcare professionals who hold key positions in their county council’s patient safety work. The findings from the studies were structured through a framework based on Donabedian’s triad (with a contextual element added) and applying a learning perspective, highlight areas that are potentially important to improve the patient safety in Swe-dish county councils. Study I showed that the conditions for the county councils’ patient safety work could be improved. Conducting root-cause analysis and attaining an organizational culture that encourages reporting and avoids blame were perceived to be of importance for improving patient safety. Study II showed that nurses perceived facilitators and barriers for improved pa-tient safety at several system levels. Study III revealed many different types of obstacles to effective surveillance of health care-associated infec-tions (HAIs), the majority belonging to the early stages of the surveillance process. Many of the obstacles described by the infection control practi-tioners restricted the use of results in efforts to reduce HAIs. Study IV of the Patient Safety Reports identified 14 different structure elements of patient safety work, 31 process elements and 23 outcome elements. These reports were perceived by patient safety officers to be useful for providing a structure for patient safety work in the county councils, for enhancing the focus on patient safety issues and for learning from the patient safety work that is undertaken. In Study V the patient safety officers rated efforts to reduce the use of antibiotics and improved communication be-tween health care practitioners and patients as most important for attaining current and future levels of patient safety in their county council. The patient safety officers also perceived that the most successful county councils regarding patient safety have good leadership support, a long-term commitment and a functional work organisation for patient safety work. Taken together, the five studies of this thesis demonstrate that patient safety is a multifaceted problem that requires multifaceted solutions. The findings point to an insufficient transition of assembled data and information into action and learning for improved patient safety.