It is our contention in this article that lifelong learning for teachers is something that is essential and fundamental for the improvement of the teaching and learning processes in education. Here, we consider some aspects related to this important subject. First, we discuss official documents dealing with teachers' lifelong learning: that is, we aim to understand the historical development of this topic and what has been proposed by international legislation. Second, we explain and discuss some theoretical views related to the theme of teachers' lifelong learning, especially those put forward by Gert Biesta. Finally, following on from what we have discussed previously, we put forward some suggestions for teachers' lifelong learning that aim to make a difference with regard to how teachers carry out their day-to-day activities.