The Swedish health care system is reorienting towards horizontal organization for care processes. A main challenge is to engage health care clinicians in the process. The aim of this study was to assess engagement (i.e. attitudes and beliefs, the cognitive state and clinical engagement behaviour) among health care clinicians, and to investigate how engagement was related to work resources and demands during organizational redesign. A cohort study was conducted, using a questionnaire distributed to clinicians at five hospitals working with care process improvement approaches, two of them having implemented Lean production. The results show that kinds of engagement are interlinked and contribute to clinical engagement behaviour in quality of care and patient safety. Increased work resources have importance for engagements in organizational improvements, especially in top-down implementations. An extended work engagement model during organizational improvements in health care was supported. The model contributes to knowledge about how and when clinicians are mobilized to engage in organizational changes.