Agency has become an essential component of discussions concerning selfhood, well-being, and care in dementia studies but the concept itself is rarely clearly defined and the use of this term can be confusing and conflicting. This paper outlines some of the key ways in which agency has been conceptualised in relation to dementia, highlighting the complexities surrounding this concept and focusing on agency in a way that is tied to our ideas about citizenship, legal and human rights. Seven key dimensions of agency are examined: embodiment, emotions, sense of agency, intentional conscious action, the social context of agency, decision-making and moral responsibility. Using a critical realist approach, this paper brings together the diverse ways in which agency has been understood into an interdisciplinary, laminated understanding of agency. This model is then used in an applied example demonstrating that this model can be used to identify the ways in which an arts intervention can support the agency of people living with dementia. This paper proposes that agency is layered, multidimensional and exists on a continuum.