There are two competing accounts explaining how increased worry about one issue affects people’s worry about unrelated issues. According to one account, it decreases worries about other issues (e.g., the finite pool of worry hypothesis). In the second account, it increases worry (e.g., generalized affect hypothesis, availability heuristics). We conducted a web-based experiment on representative samples of adults in the Czech Republic and Poland (total N = 7,051). We manipulated worry about one of three societal issues and measured the effect of this manipulation on the degree of worry about 12 unrelated issues. We also examined the underlying mechanism by looking at whether the effect was mediated by affect (a mechanism related to generalized affect) and moderated by issue similarity (a mechanism related to availability heuristics). The study provides strong evidence for a small-sized positive cross-effect of worry. Further, there are strong indications that an effect is mediated by generalized affect, specifically its valence. Our result contributes to a better understanding of how increased worry affects worries about other issues.