Accession

Accession refers to the general idea of joining or adding to. It may also refer to:


 * Accession (property law)
 * Accession, the act of joining a treaty by a party that did not take part in its negotiations; see Vienna Convention on the Law of Treaties
 * Ratification
 * EU Accession
 * Accession to the throne; not to be confused with the later ceremony of Coronation
 * Enthronement
 * Accession day, when an heir becomes monarch, and its anniversary
 * Accession to elected office; inauguration
 * Accession number (disambiguation)
 * Accession number (cultural property), a catalogue number assigned to an object when it becomes part of a library or museum collection
 * Accession number (bioinformatics), a unique identifier given to a biological polymer sequence (DNA, protein) when it is submitted to a sequence database
 * Accession (Star Trek: Deep Space Nine)
 * Accession Records, a record label created by Adrian Hates
 * Instrument of Accession, a legal document introduced in 1935, used in 1947 to enable the rulers of the princely states formerly in British India to join India or Pakistan
 * Instrument of Accession (Jammu and Kashmir), by which that state joined the Dominion of India (1947)
 * Accession Day (Jammu and Kashmir), a public holiday