Accounting for defined benefit pension plans is complex, and given the magnitude of many of these schemes relative to their corporate sponsor, understanding whether pension disclosures are value relevant is key to improving the quality of financial reports. The application of fair value accounting for pensions allows for a high level of managerial discretion with respect to ex ante accounting choices.  Utilizing a sample of firms that apply FRS-17, we examine the main determinants of the assumptions managers use to arrive at pension scheme valuations. We find significant differences in the stated assumptions across companies, auditors and actuaries. Further, managers display considerable variation in conservatism when implementing fair value accounting, and this variation is related to scheme-specific characteristics, such as asset allocation and pension plan solvency. Crucially, pension disclosures are found to be value relevant, therefore, managers are able to present pension disclosures in a more favorable light, and this is reflected in prices. As a result of the observed inconsistency in reporting across firms, and the value relevance of these disclosures, this brings into question the efficacy of fair value accounting for assessing pension values.