One of the most influential pieces of research into learning strategies was carried out by O'Malley et al (1985) and O'Malley and Chamot (1990). They interviewed groups of secondary school ESL learners in the United States and discovered a number of strategies not mentioned by Naiman et al. They classified these strategies into three groups:

• Metacognitive strategies involved thinking about the mental processes used in the learning process, monitoring learning while it is taking place, and evaluating learning after it has taken place. They included things such as organization of notes, advance preparation, etc.
• Cognitive strategies referred to the processes and behaviour that learners use to help them improve their ability to learn aspects of the language. They included processing and assimilating new information, transforming it in such a way as to associate it with the already known, organizing it to make it retrievable, rehearsing it as a skill and so on. These were manifested practically in activities such as repetition and note-taking.
• Social strategies involved putting oneself in situations where one could practise the target language.

Although all of these types of strategies appeared to contribute to language learning success, O'Malley and Chamot found 'metacognitive strategies' to be the most significant contributor. This suggests that it is important for language tutors to encourage their students to think about the language learning process, to identify their own goals, and to work out for themselves what kinds of language learning activities are going to help them to achieve those goals. In other words, we are back to learner autonomy. The more autonomous the student, the more successful he or she is likely to be at language learning.