Adjustment of Status can be done within the United States by a qualifying individual who already has a Visa to enter the country. The Adjustment of Status may only be done through a family member or employer who files a petition on their behalf. Individuals who are refugees or obtained asylum, or through a special provision can also file and adjustment of status to become permanent residents of the United States.
USCIS Adjustment of Status link: http://www.uscis.gov/green-card/green-card-processes-and-procedures/adjustment-status
USCIS Ajuste de Estatus en Español: https://www.uscis.gov/es/tarjeta-verde/tramite-y-procedimientos-para-la-tarjeta-verde/ajuste-de-estatus
I-485, Application to Register Permanent Residence or Adjust Status: http://www.uscis.gov/i-485
I-485, Solicitud de Registro de Residencia Permanente o Ajuste de Estatus: https://www.uscis.gov/es/formularios/i-485