We very often discover ourselves engaged in inner speech. It seems that this kind of silent, private, speech fulfils some role in our cognition, most probably related to conscious thinking. Yet, the study of inner speech has been neglected by philosophy and psychology alike for many years. However, things seem to have changed in the last two decades. Here we review some of the most influential accounts about the phenomenology and the functions of inner speech, as well as the methodological problems that affect its study.