This is a list of legislatures by number of members. Non-sovereign entities and unrecognized states are marked in italics.
Some of the lower and upper houses are named by approximation. For instance, the European Parliament is not a legislature with two fixed chambers of elected bodies, but rather one house of elected representatives, alongside another council of a rotating group of appointed government ministers, whose makeup changes every meeting depending on the topic being discussed. The precise nature of this organisation has been debated extensively in academic literature, with some categorising the European Union's legislature as not bicameral but tricameral or even neither.