This study addresses the obligation to provide child support on Grandparents.Its main target is to demonstrate the possibility of a direct cause of action against Grandparents.This means that Plaintiff does not have to exhaust causes of action against other obligors, like Parents (Father or Mother) present or absent.The work also examines the nature of this obligation when it has to be served by more than one person, so that the Judge has the duty to distribute the obligation between several in proportion each one's economic forces.Being a joint obligation, Plaintiff may direct a separate action against each obligor asking each one for its own portion in it.Causes of action against Grandparents include the lack of a better title or the insufficiency of it.Cause of action against Grandparents for insufficiency of a better title on its part has two separate sets of facts: exhaustion or un-payment against the preferred title; or the necessity to complement what is being paid by the preferred title.The work examines vacillation of Chilean court decisions in an analytic and critical manner.