The Montessori method was initially applied to children, but now it has also been applied to people with dementia. The purpose of this study is to systematically review the research on the effectiveness of this method using Medical Literature Analysis and Retrieval System Online (Medline) with the keywords dementia and Montessori method. We selected lo studies, in which there were significant improvements in participation and constructive engagement, and reduction of negative affects and passive engagement. Nevertheless, systematic reviews about this non-pharmacological intervention in dementia rate this method as weak in terms of effectiveness. This apparent discrepancy can be explained because the Montessori method may have, in fact, a small influence on dimensions such as behavioral problems, or because there is no research about this method with high levels of control, such as the presence of several control groups or a double-blind study.