Vaishnavism (Sanskrit: वैष्णव धर्म) is a tradition of Hinduism. Its followers worship Vishnu or his avatars, mainly Rama and Krishna as the highest, or original God. This worship in different perspectives or historical traditions addresses God under the names of Narayana, Krishna, Vāsudeva or more often "Vishnu", and their associated avatars. Its beliefs and practices, especially the concepts of Bhakti and Bhakti Yoga, are based largely on the Upanishads, and associated with the Vedas and Puranic texts such as the Bhagavad Gita, and the Padma, Vishnu and Bhagavata Puranas.

The Yadavas of the Mahabharata period were known to be the followers of Vaishnavism, of which Krishna was the leader: they were Gopas (cowherd) by profession, but at the same time they held the status of the Kshatriyas, participating in the battle of Kurukshetra. The present Ahirs are also followers of Vaisnavism.

Thehe followers of Vaishnavism are referred to as Vaishnava(s) or Vaishnavites. A large percentage of Hindus are Vaishnavas, with the vast majority living in India. Awareness, recognition, and growth of the belief has significantly increased outside of India in recent years. The Gaudiya Vaishnava branch of the tradition has significantly increased the awareness of Vaishnavism internationally, since the mid-1900s, largely through the activities and geographical expansion of the Hare Krishna movement, primarily through ISKCON and more recently, through several other Vaishnava organizations conducting preaching activities in the West.