Some theories in economics and psychology propose that background uncertainty, which is uncertaintycthat is independent of a person’s actual decision, can alter people’s risk-taking behavior with respectcto that decision. However, previous empirical research mostly relying on singlecexperiments iscinconclusive regarding the existence of this effect. Here, we systematically investigate the effect ofcbackground uncertainty on decision-making. After reviewing the literature, we argue that two types ofcbackground uncertainty should be distinguished: (a) background ambiguity, where the decision makercdoes not know the probability of the outcomes of the background event, and (b) background risk, where the outcome probabilities are known. We tested the hypotheses (i) that background uncertainty does affect risk-taking in the decision at hand, and (ii) the type of background uncertainty moderates that effect. In four experiments (total N 863), we induced background uncertainty (ambiguity or risk) using different methods and measured risk-taking with multiple behavioral tasks. We did not find a significant effect of background uncertainty on risk-taking behavior.