Adaptability is purported to be a key mental resource and refers to an individual’s cognitive, behavioral, and emotional regulation (or adjustment) in situations of change, novelty, and uncertainty. Psychological flexibility refers to a person’s capacity to allow experience and acceptance of negative thoughts and feelings with mindful awareness guided by a commitment to goal-driven action according to their self-chosen values. It is important to disentangle these cognate constructs—adaptability and psychological flexibility—so that the unique variance attributable to each can be estimated, and interventions and resources can be directed with greater precision. The current study explored the potential overlap between adaptability and psychological flexibility by conducting an online cross-sectional survey (n = 205), with measures of adaptability, psychological flexibility, wellbeing, and psychological distress. A confirmatory factor analysis suggested considerable overlap, but sufficient discrimination between the two constructs. Structural equation modelling showed that adaptability was related to psychological wellbeing, but not related to psychological distress after accounting for the effects of psychological flexibility.