This project page contains the files needed to use the hierarchical Bayesian parameter estimation procedure for Cumulative Prospect Theory described in Nilsson, Rieskamp, & Wagenmakers (2011). For any questions or comments, please contact Håkan Nilsson at firstname.lastname@example.org. **Note.** The original code had some minor errors (see downloadable file *Erratum*). The model code was updated in December of 2018 and is now fully in line with the model originally outlined by Tversky and Kahneman (1992). **Related refrences:** Nilsson, H., Rieskamp, J., & Wagenmakers, E-J. (2011). Hierarchical Bayesian parameter estimation for cumulative prospect theory. Journal of Mathematical Psychology, 55, 84-93. Tversky, A., & Kahneman, D. (1992). Advances in prospect theory: Cumulative representations of uncertainty. Journal of Risk and Uncertainty, 5, 297-323.