Background: Care staff often lack knowledge, confidence, skills, and competency to provide optimal care for people with dementia. Dementia education can increase staff competency and wellbeing along with the actual care of people with dementia. Several factors can affect the effectiveness of dementia education; however, it is not yet established which factors are most important. Objective: The aim of the overview of systematic reviews is to investigate the effectiveness of dementia education for care staff on staff-related outcomes and influencing factors, identify needs for future research, and provide practical recommendations for effective dementia education. Methods: Systematic searches were conducted in PubMed, Cinahl, and PsycInfo accompanied by manual citation and reference searches. For inclusion, reviews must report on either effectiveness of one staff-related outcome or on factors influencing the effectiveness of dementia education for care staff. Quality assessments were conducted using AMSTAR2. After data extraction, results on effectiveness were structured according to satisfaction, learning, behavior, and results. Results on contributing factors to effectiveness were categorized into program, personal and organizational factors. All results were qualitatively summarized and reported according to the PRISMA statement. Results: Seventeen systematic reviews of low to medium quality were included. Dementia education positively affects knowledge, self-efficacy, and attitudes towards dementia and people with dementia. Care staff experienced improvements in communication and behavior management and reduction in behavioral symptoms of dementia of people with dementia was seen as well. Most reviews found no changes within restraints, medication, staff well-being and job satisfaction. Factors contributing to effectiveness are relevant and directly applicable content, active learning methods, classroom teaching combined with practical experience, theory-driven approaches and feedback sessions. Finally, the instructor needs to be experienced within dementia and sensitive to the needs of participants. Conclusion: There is no one-size-fits-all in dementia education: however, perceived relevance and applicability are key elements for effective dementia education. Due to low quality of primary studies, further research of high methodological quality is needed on effectiveness of dementia education on staff behavior, wellbeing, and job satisfaction as well as on influencing factors and their impact on mechanisms of change.