The Hungarian National Assembly is an active player in interparliamentary cooperation within the European Union. Certain parts of the EU's founding and amending treaties refer to the role of national parliaments and the significance of interparliamentary cooperation in the EU.

In the current EU Treaty, the Treaty of Lisbon, several articles and two protocols refer to the role of national parliaments, thus allowing for greater involvement of national parliaments in the activities of the European Union than before and widening the framework within which national parliaments can express their views on draft legislative acts of the European Union and on matters of particular interest to them. The aims of interparliamentary cooperation within the European Union, through these broader competences, can be summarised in three main categories.

Firstly, it is of particular importance to support the exchange of best practices and information on the functioning of parliaments in the Member States in order to strengthen parliamentary control and influence over the role of governments in EU decision-making. On the other hand, it is important to ensure the effective exercise of parliamentary competencies in the context of controlling the application of the principles of subsidiarity and proportionality. Finally, it is also important to promote cooperation with non-EU countries. Overall, the National Assembly's aim is to continue to give national parliaments, as guardians of the people's sovereignty, a greater role in influencing European Union policies.

There are multiple key forums for interparliamentary cooperation within the European Union. In addition to the longer-standing forums (e.g. the Conference of the Speakers of European Union Parliaments and the Conference of Parliamentary Committees for Union Affairs of Parliaments of the European Union, COSAC), the Treaty of Lisbon and the challenges facing the Union have increased the need to create new interparliamentary forums. In addition to Member States' national parliaments and European Parliament delegations, the participation is open to parliamentary delegations from candidate countries as observers, while other participants may be invited on a case-by-case basis. This practice differs from that of the permanent interparliamentary forums (e.g. the Parliamentary Assembly of the Union for the Mediterranean), which have permanent membership and thus include full participation of members of parliament from non-EU countries.
    
The Conference of Speakers of European Union Parliaments is the highest forum for interparliamentary cooperation in the European Union, with the main task of determining the framework and strategic objectives of parliamentary cooperation. The Conference of Speakers decides on the establishment of further permanent interparliamentary forums, such as the various interparliamentary conferences. Permanent interparliamentary conferences include the following:

• Conference of Parliamentary Committees for Union Affairs of Parliaments of the European Union (COSAC);
• Interparliamentary Conference for the Common Foreign and Security Policy (CFSP) and the Common Security and Defence Policy (CSDP);
• The Inter-Parliamentary Conference on Stability, Economic Coordination and Governance in the EU;
• Joint Parliamentary Scrutiny Group on Europol (European Union Agency for Law Enforcement Cooperation), a body composed of members of national parliaments and the European Parliament.

Other regular forums for interparliamentary cooperation in the EU include the interparliamentary committee session convened by the European Parliament and national parliaments to jointly evaluate the activities of Eurojust, the European Union Agency for Criminal Justice Cooperation.

In addition to the regular interparliamentary conferences, the national parliament of the Member State holding the rotating presidency of the Council of the European Union organises other parliamentary committee chairs' meetings every six months, which are less institutionalised formats based on interparliamentary practice. The topics of the meetings of committee chairs are generally in line with the priorities of the presidency-in-office.
    
The relationship between national parliaments and the European Parliament is crucial for parliamentary cooperation in the European Union. Various forums for cooperation exist, such as interparliamentary meetings organised jointly by the European Parliament and the parliament of the Member State holding the rotating presidency, high-level conferences and interparliamentary committee sessions organised by the European Parliament's committees.

The Parliamentary Assembly of the Union for the Mediterranean and the EuroNest Parliamentary Assembly (Eastern Partnership) are two of the European Union's parliamentary platforms for cooperation with third countries. Another element of the European Union's parliamentary cooperation with third countries is constituted by the Asia-Europe Parliamentary Partnership Meetings (ASEP).

An important element in parliamentary diplomacy is the participation of national parliaments in EU twinning or assistance programmes in third countries. The Hungarian National Assembly is the most successful among the parliaments of EU Member States in winning and implementing such programmes. The Hungarian National Assembly is also actively involved in the latest EU initiative for parliamentary capacity building in third countries, the so-called Inter Pares – Parliaments in Partnership, EU Global Project to Strengthen the Capacity of Parliaments, funded by the European Commission.

In the context of EU interparliamentary cooperation, it is also important to note two key tools supporting the exchange of information between national parliaments: the  Platform for EU Interparliamentary Exchange, IPEX, and the research and documentation network jointly organised by the European Parliament and the Parliamentary Assembly of the Council of Europe, ECPRD.