This report describes the development and preliminary psychometric properties of the Decision-Making Involvement Scale for individuals with dementia and family caregivers. Data were collected from 217 individuals with dementia and their respective caregivers. Principal axis factor analysis, Kendall tau, and Pearson correlations were used to determine the Decision-Making Involvement Scale's psychometric properties, mean differences of caregiver and individual with dementia, and the relationship between scores of Decision-Making Involvement Scale and measures of well-being. Analyses support a reliable, 1-factor solution of the Decision-Making Involvement Scale for both individuals with dementia and caregivers. Socio-demographic, impairment, and well-being variables are differentially related to the perceptions of how involved the individual with dementia is in decision making. The Decision-Making Involvement Scale provides useful information about daily decision making of an individual with dementia, and it shows promise as a means for understanding the relationship between decision-making involvement and well-being of individuals with dementia and caregivers.