This paper investigates changes in the attitudes of translators towards faithfulness to the original text and towards the readability of non-fiction English-Japanese translations in Japan during the 1970s. Specifically, it adopts the framework of translation norms proposed by Gideon Toury (1995), who advocates a socio-cultural approach to translation and focuses on the initial norms of ‘acceptability’ and ‘adequacy’. Although Japanese translators had previously been more concerned with fidelity and literal translation, from the 1970s onward they were becoming more concerned with conforming to Japanese cultural and linguistic norms, perhaps in response to changing expectations towards translations on the part of readers. This trend of adhering to ‘acceptability’ continued to gain increasing popularity into the following decades, although the older norm of ‘adequacy’ still persisted.