The Impermanence Awareness and Acceptance Scale (IMAAS) was developed to operationalize and measure the construct of impermanence. It assesses two factors: (1) impermanence awareness, which refers to the recognition that all phenomena are transient, and (2) impermanence acceptance, which denotes an attitude of openness towards the transient nature of all phenomena. The common latent factor method was used to identify potential common factors and response biases. Configural and metric invariance tests were used to validate the factor structure. Confirmatory factor analysis showed a good model fit for a two-factor structure, comprising impermanence awareness and impermanence acceptance. The 13-item IMAAS showed good convergent validity with similar constructs, such as death acceptance, and good discriminant validity with related but different constructs, such as mindfulness. Both impermanence awareness and acceptance were positively correlated with psychological well-being. The IMAAS is a valid tool to assess awareness and acceptance of change.