The Quechua community of Q'eros in the Andes of southeastern Peru is renowned in the Cusco region and within various circles (layman, scholarly, esoteric, tourist). The Q'eros are also known nationally and internationally for their continued practice of indigenous customs such as musical rituals that other Andean communities no longer maintain. This dissertation shows how the Q'eros' two principal indigenous song genres, Pukllay taki (Carnaval songs) and animal fertility songs, serve as active forms of social and cosmic renewal, regeneration, and reproduction. Regenerative processes through musical performance occur on many levels: the revitalization of relationship with the cosmological spirit powers, the Apu (mountain spirits) and Pacha Mama (Mother Earth); the renewal and reinforcement of social ties and women's and men's roles; and the re-creation and reproduction of cosmological worldview. This dissertation shows how the Q'eros actively regenerate, re-create, and reproduce social and cosmic relationships and cosmological perceptions through their music-making. Three Andean concepts that the Q'eros specifically name and describe show how music serves in the regenerative processes of social and cosmic relationships, and in cosmological worldview: animu, yanantin, and ayni. Animu is the animated essence that is in every person, object, and invisible spirit, which propels the life-governing concepts of yanantin (complementary duality) and ayni (reciprocity). Yanantin is the union of two contrasting and interdependent parts that are in movement with one another, in continual search of equilibrium, and with a meeting and overlap in a center. The Q'eros articulate the reproduction of the cosmological worldview of yanantin in performance roles and instrument pairs. I argue that yanantin is also expressed on the micro level of relationship between vocal and pinkuyllu (flute) melodies in song structure and between songs, as well as on the macro level of communally sung expressions of joy and grief. Ayni is the most fundamental and life-sustaining form of reciprocal exchange in Q'eros, and many other, Andean communities. The Q'eros give offerings in many forms (food, drink, special ingredient bundles, and songs) to the Apu and Pacha Mama in exchange for the well-being of the people and their animals. Q'eros' singing and flute playing are active forms of ayni, in that they are musical offerings that are sent out through samay (breath, life essence and force) in propitiation. To ensure receipt of the songs by the spirit powers, the Q'eros employ a vocal technique they call aysariykuy ("to pull"): ends of phrases are sung in prolonged, held tones with a final, forced expulsion of air. This is the Q'eros' active way to send the song out so that it will reach the spirit powers. Once the spirit powers successfully receive a song, the powers will be able to reciprocate beneficially. The tension caused by the desired necessary, successful reciprocation from the spirit powers to the people, and remembrance of times when that has not been the case, often result in the sung expression of grief and anxiety. The singing of grief and anxiety rebuilds sociability that loss and death have disrupted. By contrast, the joyful communal singing in the annual Carnaval celebration serves to re-establish social ties and renew social relationships in the community, a practice that balances the communal singing of grief during animal fertility. This dissertation shows that the regular and expected release of joy and grief through music contributes to individual and communal balance and healing. The dissertation details the social and cosmic regenerative processes throughout in the form of detailed ethnographic description; insight from the author's participation; interviews; analyses of musical detail and aesthetics of specific audio examples; musical transcriptions (both in five-line staff and alternative transcription design to show cosmological view imbedded in song structure); and transcriptions, translations, and analyses of song texts.