Though generally under-utilised in spoken English, the passive voice plays a crucial role in formal, written English (Biber et al., 1999). An understanding of how the passive voice operates in English writing is therefore a vital skill for EFL learners in secondary and higher education so that they may be able to both understand and produce fluent and accurate formal English writing. Using samples of Japanese high school learners' writing, this paper sought to shed light on why many Japanese EFL learners struggle to produce accurate passive constructions in English writing. The paper begins by examining how the passive voice is used in English, focusing on core passive forms, "pseudopassives" (Balcom, 2001), agency, and transitivity. Conveying a sense of objectivity (such as through the use of agentless passives) is also highlighted as a crucial feature of the use of the passive voice in formal, written English. Comparing the use of the passive voice in Japanese to its use in English reveals some structural and functional similarities, although there are some syntactic differences--particularly in relation to verb conjugation. The role of transitivity is also a key point of difference between the two languages. Unlike in Japanese, intransitive verbs cannot be passivised in English. Japanese EFL learners are often able to produce fluent, accurate passive structures in English, especially when the agent and patient are clearly identified. However, many Japanese EFL learners struggle with agentless passives in English--whereas in Japanese agents are almost always specified (Watanabe et al., 1991), the agent is often omitted in written English. This can lead to L1 transfer, the (incorrect) iteration and fossilisation of novel passive constructions. Increasing Japanese EFL learners' exposure to different varieties of English passive constructions is suggested as a potential means of remedying this problem. In addition, focusing on correct passive structure form (through explicit instruction and spoken/written corrective feedback) during in-class written production may also prove to be effective.