Legislative functions of federal second chambers are not a homogeneous set of powers, but require comparison and classification. First, the paper will examine the legislative functions of the second chambers of those European states that have a federal or quasifederal character (Austria, Belgium, Bosnia and Herzegovina, Germany, Italy, Russia, Spain, Switzerland, United Kingdom). Second, the paper addresses the normative concept of the legislative functions of federal second chambers: what is the particularly federal rationale behind these legislative powers, and are there other constitutional rationales as well? Do some legislative functions serve purposes of federalism better than others and does a dichotomy between ‘weak-form’ and ‘strong-form’ veto powers apply in this context? This will also require some discussion on whether perfect or imperfect bicameralism and the requirements of internal decision-making play a role in this regard.