Background Swedish healthcare organizations are investing heavily in internal reforms. Lean has been frequently used as an overall concept to improve care processes and decrease costs. Some evidence shows positive results, especially if work environment issues are considered in parallel with other desired outcomes. However, there are considerable difficulties in evaluating lean as a concept since its application and interpretation seem to vary widely. Further, like for other management concepts, lean outcomes crucially depend on the implementation process. Aim This program investigates implementations of lean and lean-like developments of processes of care, and how these affect the working conditions, health, and performance of healthcare employees. We also investigated organizational factors and conditions that mediated specific outcomes. Method Mixed method design: questionnaire to employees (n=880) and managers (n=320), qualitative interviews (n=55) and observations with follow up during three years. Five hospitals were selected, and within them five units that were connected by their flow of acute care patients, i.e. the emergency unit, the medical and surgical emergency ward (or ICU at small hospital) as well as one medical and one surgical ward. Initially we used qualitative-driven analyses and thereafter quantitative-driven mixed method analysis. Results The implementation strategies varied between the hospitals and between the strategic and operative levels. Strategic managers also used different approaches to overcome the gap between strategic and operative levels. Operative managers shared similarities in their stepwise and coaching approaches encouraging participation among employees, but differences regarding how assignments were delegated. Social capital and attitudes among health care profession were of importance for employees’ work engagement and active engagement in development work.