In Tibetan Buddhism, Ngöndro (Tibetan: སྔོན་འགྲོ།, Wylie: sngon 'gro, Sanskrit: pūrvaka) refers to the preliminary, preparatory or foundational practices or disciplines (Sanskrit: sādhanā) common to all four schools of Tibetan Buddhism and also to Bon. They precede deity yoga. The preliminary practices establish the foundation for the more advanced and rarefied Vajrayana sādhanā which are held to engender realization and the embodiment of Dzogchen, Heruka and Mahamudra.