In this article, I argue that to have competence is to have the possibility, by performing a special kind of act, to change legal positions. To gain a better understanding of the nature of this possibility, we may distinguish between (i) competence as permission, (ii) competence as a practical possibility, and (iii) competence as (what we might call) a hypothetical possibility. I defend a version of (iii), which has it that to have competence is to have a in the following sense: if the agent (in an adequate situation) performs a C-act (and thus goes about it in the right way), he brings about the intended change of position. And this is fully consistent with his not having the practical possibility to perform the C-act, perhaps because of physical impediment. I therefore suggest the following definition of the concept of legal competence: A person, p, has the competence to change a legal position, LP, if, and only if, there is an action, a, and a situation, S, such that if p in S performs a (and thus goes about it in the right way), p will, through a, change LP.