Objective This study aimed to survey health care professionals in Sweden on the factors that they believe have been most important in reaching the current level of patient safety and achieving safer care in the future as well as the characteristics of the county councils that have been the most successful in achieving safe care. Methods The study population consisted of 222 patient safety officers, that is, health care professionals with strategic positions in patient safety work in the county councils. A postal questionnaire was used for data collection. Results The survey response rate was 70%. The factors that were considered most important for the current level of patient safety were efforts to reduce the use of antibiotics; Swedish patient safety law; and internal discussions with the county council management, heads of health care units, health care providers, and so on. The factors that were considered most important to achieve safer care in the future were improved communication between health care practitioners and patients, improved organizational culture, improved communication, and patient safety knowledge as a compulsory component of basic education for health care practitioners. Conclusions Several factors rated highly for achieving the current level of patient safety are part of the government-supported financial incentive plan. Patient safety is attributed to a broad range of factors, and many solutions might contribute to improved patient safety in the future. The most successful county councils are characterized by leadership support for patient safety, well-organized patient safety work, long-term commitment to patient safety, and an organizational culture that is conducive to patient safety.