In a number of psychological disciplines, experience sampling studies are used to investigate when and why individuals vary in their cognitions, feelings, or personality states, to name just a few examples. However, to validly answer such research questions, researchers have to use reliable and valid measures of such intraindividual or within-person variability. Following Baird, Lucas, and Donnellan (2017), the present study uses data from two experience sampling studies to investigate whether response style variability can be assessed in a reliable way, whether variability measures are related to such response styles, and whether it is important to control for response styles in later analyses. We found that individuals differ in their response style variability and that these differences can be reliably assessed. Furthermore, response styles were moderately related to personality indicators, affect, and self-esteem variability. They were not associated with any of the outcome measures, so that most results remained unchanged when controlling for these differences. Nevertheless, our results indicate that researchers should additionally assess response styles when studying phenomena involving intraindividual variability.