The Portuguese nobility was a social class enshrined in the laws of the Kingdom of Portugal with specific privileges, prerogatives, obligations and regulations. The nobility ranked immediately after royalty and was itself subdivided into a number of subcategories which included the titled nobility and nobility of blood at the top and civic nobility at the bottom, encompassing a small, but considerable proportion of Portugal's citizenry.
The nobility was an open, regulated social class. Accession to it was dependent on a family's or, more rarely, an individual's merit and proven loyalty to the Crown in most cases over generations. Formal access was granted by the monarch through letters of ennoblement and a family's status within the noble class was determined by continued and significant services to Crown and country. Living outside the laws of the nobility immediately revoked an individual's status and that of his descendants.