Objective: The Outcome Measures in Rheumatology (OMERACT) Filter provides guidelines for the development and validation of outcome measures for use in clinical research. The "Truth" section of the OMERACT Filter requires that criteria be met to demonstrate that the outcome instrument meets the criteria for content, face, and construct validity. Methods: Discussion groups critically reviewed a variety of ways in which case studies of current OMERACT Working Groups complied with the Truth component of the Filter and what issues remained to be resolved. Results: The case studies showed that there is broad agreement on criteria for meeting the Truth criteria through demonstration of content, face, and construct validity; however, several issues were identified that the Filter Working Group will need to address. Conclusion: These issues will require resolution to reach consensus on how Truth will be assessed for the proposed Filter 2.0 framework, for instruments to be endorsed by OMERACT. © 2014. All rights reserved.