After a presentation of new states accession to the European Union starting with the first wave of extension (from six to nine) up to the fourth wave of extension (from fifteen to twenty seven) communities accession weight is analyzed, revealing the accession requirements, pre-accession funds, accession procedure stages, respectively: pre-accession phase, communitarian phase – approval from communitarian institutions, international phase – accession agreements conclusion. The juridical nature of accession agreements and membership termination are also discussed.