Chemical scientists and engineers are interested in controlling chemical processes to attain specific goals, from synthesizing a desired substance to hindering a particular transformation. Nevertheless, students typically have few opportunities to develop the understandings and practices that are required to effectively engage in chemical control. In this study, we investigated similarities and differences among individuals with different levels of expertise in chemistry in the ways they think about how to control and act to control a chemical reaction. Our findings revealed that all types of study participants engage in the manipulation of similar control parameters but with different approaches and purposes. In particular, we observed a shift from a focus on physical to chemical factors, from experienced-based to model-based reasoning, from qualitative to quantitative methods, and from trial-and-error to guided investigation approaches in the thinking and acting of the more novice to the more expert participants in our study.