Y mae Erthygl 3 y Cytundeb ar Hawliau’r Plentyn yn sicrhau y dylai sefydliadau sy’n ymwneud â phlant weithio dros yr hyn sydd er eu buddiannau gorau: 

Dylai pob sefydliad sy’n ymwneud â phlant weithio at yr hyn sydd orau i bob plentyn.*

* Y mae’r testun hwn yn dod o fersiwn gryno o’r Cytundeb yn unig.  Nid yw testun llawn y Cytundeb wedi’i gyfieithu i’r Gymraeg.  Fodd bynnag, y mae cyfieithiad Saesneg yr erthygl hon fel a ganlyn:

"1. In all actions concerning children, whether undertaken by public or private social welfare institutions, courts of law, administrative authorities or legislative bodies, the best interests of the child shall be a primary consideration.

2. States Parties undertake to ensure the child such protection and care as is necessary for his or her well-being, taking into account the rights and duties of his or her parents, legal guardians, or other individuals legally responsible for him or her, and, to this end, shall take all appropriate legislative and administrative measures.

3. States Parties shall ensure that the institutions, services and facilities responsible for the care or protection of children shall conform with the standards established by competent authorities, particularly in the areas of safety, health, in the number and suitability of their staff, as well as competent supervision."