The Committee on Industrial Organisation was established in the early 1960s to evaluate the level of preparedness of Irish industry for the imminent dismantling of the country's protectionist trade barriers. The Committee's sectoral reports list the 900 or so manufacturing firms that it surveyed and that together accounted for more than half of Irish manufacturing employment. From a range of archival sources, this article identifies the nationality of ownership of most of these firms, alongside their date of establishment and level of employment in 1960. Industrial grants data are used to strip out export‐oriented businesses that began to arrive in the 1950s. This makes it possible to estimate the employment share and sectoral presence of tariff‐jumping foreign firms. The latter is analysed through the lens of modern perspectives on foreign direct investment. The article also enhances our understanding of the interest‐group politics of the trade liberalization process.