The shift in the parent-child relationship during the transition to adulthood presumes that emerging adults progress toward financial self-sufficiency. Research indicates that financial parenting contributes to success in this transition, and these effects extend beyond the financial domain. Nevertheless, there is a lack of theory-based tools to measure relevant financial parenting aspects. By applying the six dimensions of interpersonal behaviors outlined in the Self-Determination Theory (SDT), the current study develops a scale targeting the interpersonal style of financial parenting. To validate the scale, it also tests seven preregistered hypotheses predicting internal structure and associations with relevant external variables in a sample of 600 emerging adults (Mage =24.94, SDage = 3.03, range 19-29 years; 52.3% women). The sample, diverse occupational status characteristics, was recruited from an online survey panel using the controlled quota sampling strategy. While study results provide modest evidence for a hypothesized six-factor structure and advocate instead for a more parsimonious two-dimensional one, results provide evidence for the new scale's convergent, discriminant, criterion, and incremental validity. This is the first study that brings SDT into family financial socialization research and opens a new line of research on family financial socialization, achievement of financial self-sufficiency, and emerging adults' wellbeing.