Cook started his career as a lecturer in EFL and Director of Language Service in London, and during this time he published many innovative EFL textbooks. In 1978 he became a lecturer in Applied Linguistics at the University of Essex, and in 2004 he got his professorship at Newcastle University. In the 1970s and 1980s Professor Cook introduced various research methods in second language acquisition research. He favoured an experimental approach to second language research and conducted various experiments. He wrote a very successful textbook about Noam Chomsky's theories, and related Universal Grammar to second language acquisition and teaching. He also published papers on second-language teaching, and developed Computer-Assisted Language Learning programs for learning English as a foreign language, including adventure games and syntactic parsing programs. In the early 1990s he proposed the multi-competence approach to second-language acquisition. Multi-competence is "the knowledge of two languages in one mind", and it holds that those who know more than one language have different minds from those with only one language, because knowing two languages changes the way people use their first language, and even the way they think. These multicompetent individuals should be called "L2 users" rather than "second language learners", because the word "second" has negative connotations, and the word "learner" should only be applied to those who are learning a language. All human beings have the potential for becoming multi-competent, so monolinguals are not indicative of what the human mind can achieve. This has implications for language learners and teachers, for instance the purpose of L2 learning is to become a multicompetent user of more than one language, not to become a copycat of a native speaker of another language; the native speaker is not the best L2 teacher; L2 learners are allowed to use their first language in the classroom. Also, teachers and learners must bear in mind that L2 learning changes how people think. In a paper dated 1997 Cook first argued that knowledge of more than one language can change how people think. He then provided evidence in the first ever workshop devoted to the topic and showcased research from a variety of disciplines and languages in his latest edited volume. Vivian Cook has also researched writing systems, especially the English one. He published a successful textbook about English orthography, co-edited a volume on how people read and write a second language, and is currently editor of the journal '. In 2004 he published a successful popular book called ', which explains to the layperson how English orthography works in an entertaining but authoritative way. Vivian Cook has given talks all over the world, in Europe, China, Japan, Korea, Malaysia, Singapore, Gaza, Iran, Israel, Canada and the US.
