Objective: In a budget-constrained health care system, decisions regarding resource allocation towards research and implementation are critical and can be informed by cost-effectiveness analysis. The objective of this study was to assess the societal value of conducting further research to inform reimbursement decisions and implementation of cost-effective psychotherapy for clusters B and C personality disorders (PDs). Methods: Value of information and value of implementation analyses were conducted using previously developed cost-effectiveness models for clusters B and C PDs to evaluate the parameters that contribute to most of the decision uncertainty, and to calculate the population expected values of perfect information (pEVPI) and perfect implementation (pEVPIM). Results: The pEVPI was estimated to be (sic)425 million for cluster B PDs and (sic)315 million for cluster C PDs, indicating that gathering additional evidence is expected to be cost-effective. The categories of parameters for which reduction of uncertainty would be most valuable were transition probabilities and health state costs. The pEVPIM was estimated to be (sic)595 million for cluster B PDs and (sic)1,372 million for cluster C PDs, suggesting that investing in implementation of cost-effective psychotherapy is likely to be worthwhile. Conclusions: The societal value of additional research on psychotherapy for clusters B and C PDs is substantial, especially when prioritizing information on transition probabilities and health state costs. Active implementation of cost-effective treatment strategies into clinical practice is likely to improve the efficiency of health care provision in The Netherlands. , International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc.