Adaptive behaviour in the European Parliament: Learning to balance competing demands

<jats:p> Parliamentary institutions and partisan norms are complex and new members of parliament are unlikely to possess an innate awareness of optimal behaviour. This paper examines how new legislators adopt the behavioural patterns of incumbent members in the Sixth European Parliament. The latter provides an excellent opportunity to study such adaptive behaviour; in addition to newly elected members from 15 former states, new members from ten accession countries took seats for the first time. We examine how voting behaviour differs between new members from the 15 former states, new members from accession countries, and incumbent members. Our analysis shows that new members from former states defect less from their European political group than incumbents, while new accession country members defect more. Over time, the differences between these groups disappear. </jats:p>