This study provides comparative findings on the impact of adoption of International Financial Reporting Standards (IFRSs) on the value relevance of reported accounting and non-accounting information in a set of six countries with a British accounting heritage but divergent harmonization paths leading up to IFRS adoption. The countries included in the sample are the United Kingdom, Australia, Hong Kong, Singapore, Malaysia and South Africa. The aim of this study is to advance the accounting value relevance literature through a more comprehensive analysis – including multiple models of the value relevance of primary accounting numbers, the addition in these models of textual disclosures about intellectual capital, longer pre- and post-IFRS adoption periods, and a larger cross-section of countries – than prior studies. This study is motivated in terms of making a contribution to the financial reporting research literature on value relevance and intellectual capital disclosure, as well as providing findings that can be informative to accounting standards setters. The sample for this study consists of 2275 firm-year observations for 325 listed companies, from the six chosen countries, for the period between 2002 and 2008.  The results of this study have provided an increased understanding of the level and direction of changes in value relevance of accounting numbers under the IFRS regime compared to alternative countries’ local GAAPs which had varied in degree of harmonization with IFRSs. It then provides insight about the issue of whether off-balance sheet company value contained in intellectual capital, particularly in new economy industries, is weakening the value relevance of accounting numbers. Findings of this study should be of much interest to corporate management, accounting standard setters, investors and others interested in capital market based accounting research. This greater understanding could be translated into improved decision making for these three main financial statement groups