Stipulation gives us a degree of control over meaning. By stipulating how I will use a term I am able to determine the meaning it will receive on future occasions of use. My stipulation will affect the truth conditional content of my future utterances. But the mechanisms of stipulation are mysterious. As Cappelen ([2018]. Fixing Language: An Essay on Conceptual Engineering. Oxford: Oxford University Press. https://doi.org/10.1093/oso/9780198814719.001.0001) argues, meaning is typically determined in an inscrutable way by a myriad of external factors beyond our control. How does stipulation override these factors? And the powers of stipulation are limited. Firstly, the power of stipulation is typically short-lived. Secondly, some stipulations simply don’t get off the ground. What explains the limits of stipulation? I consider two related approaches to stipulation and argue that they are unable to capture stipulation’s metasemantic effects. I then provide an explanation of the metasemantic effects of stipulation: Stipulation determines meaning by determining the word use it is fitting to hold the speaker to. This account is able to capture the mechanisms and limits of stipulation, whilst also explaining why we should care about stipulative success. I close by briefly drawing out some lessons for conceptual engineering.