This study analyses party group cohesion and patterns of defections of national party delegations from party group lines in the present European Parliament, using a total of 1,370 roll call votes. The study confirms previous findings according to which party groups in the EP show (surprisingly) high levels of cohesion. In addition and notwithstanding that, it reveals the circumstances under which MEPs and their national delegations are more likely to defect. Among other factors, it was analysed how the nature of the candidate selection process, the electoral system, and the relationships between MEPs and their home parties influence these defections. Assuming that MEPs have three different goals (re-election, office, and policy) and want to first of all secure re-election, one can theoretically expect that those MEPs whose chances of re-election are more dependent on national parties than others (due to their specific candidate selection process or their relationship to their home party) are more willing to vote against the party group line, if a conflict between party group and national party emerges. Empirically, this is confirmed. In other words, MEPs in general are very well aware of their specific situation. They know who deserves their primary attention and they act accordingly.