<p>It has been argued that small, new, and protest parties should overperform in European Parliament elections (EPEs). However, ongoing transformations of European party systems call for a revaluation and potential refinement of mechanisms driving the expected differences in vote outcome between second-order EPEs and first-order national elections. This article strives to do that by studying parties that are not easily classifiable within the traditional party typology framework yet can be classified as small, new and protest–the Pirates–and parties that started as protest parties; however, with gradual success, many of them integrated into the political mainstream–the Greens. Comparative analysis of the performance of these party types thus allows a reassessment of one of the key theories of European comparative electoral behaviour while also evaluating the effects of the change in parties’ function in/towards the system on electoral success in different types of elections. Somewhat contrary to expectations, the findings show that being a Pirate party does not provide a comparative advantage in EPEs, while being a Green party does. However, the latter’s advantage is conditioned by participation in government and party size.</p>