The conventional wisdom regarding experimental research states that experiments are widely valued for their internal validity but that they lack external validity. External validity is commonly used to refer to the extent to which the uncovered causal relationships hold over variations in persons, settings, treatments, and outcomes. The threats to external validity fall into two broad classes: those dealing with generalizations to populations of persons (population validity) and those dealing with the environment of the experiment (ecological validity). In comparison with other methods, experiments do not encounter specific problems regarding population validity. But, when it comes to ecological validity, a weakness of experiments is that they often use artificial stimuli that do not accurately reflect people’s everyday world. In this methods case, we will focus on measures to overcome these problems of external validity by discussing the research design of a project on the prevalence of political gender stereotypes in Flanders (Belgium). More in particular, we will discuss how we deal with five different elements of external validity: whether the participants resemble the actors who are in real life confronted with these stimuli, whether the context within which actors operate resemble the context of interest, whether the stimulus used in the study resembles the stimulus of interest in the real world, whether the treatments and outcome measures resemble the actual outcomes of theoretical or practical interest, and whether the experiment will be replicated across different settings.