Person-centeredness first emerged as a concept in dementia care in the 1980s. Nearly 40 years later, it has no universal definition, which limits operationalization and implementation of care and supportive services, measures, interventions, policy, and regulation for people with dementia. Thus, a scoping review of the current definitions of person-centeredness in US dementia care was conducted. Of the 71 included studies, there was considerable variability in elements/themes, complexity, and cited theories; the most common themes were needs and preferences, relationships, and personhood, all of which were present in at least half of the studies' definitions. Importantly, more than 150 articles that were reviewed did not contain a definition, despite including the term in their titles or abstracts. Further investigation in pursuit of a more nuanced conceptualization of person-centeredness that includes these key themes, while also addressing concerns about applicability to diverse cultures and contexts (e.g., organizations and systems), is recommended.