In the religious ethics of the Buddhist and Christian traditions, friendship appears as a principle of seeking happiness for others. In the Mahāyāna Buddhist tradition, friendship - a possible translation of the Sanskrit term maitrī - consists of the resolution to seek the happiness of all sentient beings, to generate states of meditative concentration capable of transforming the practitioner's mind. The practitioner, then, cultivates non-hatred, which is the nature of friendship, and thus directs their actions to lead sentient beings to happiness. In the Christian tradition of Thomas Aquinas, the love of friendship - from the Latin, amor amicitiae - expands on Aristotelian virtuous friendship and seeks delightful goods not only for virtuous friends, but for all human beings, since they share the same dignity as sons of God. In Aquinas's love of friendship, the person is the absolute good loved in themselves, not for any other purpose that seeks self-benefit. In both cases, in the form of maitrī or amor amicitiae, the cultivation of love-friendship transforms the practitioner's mind and habits, impacting their actions within society. Taking as main references the works 大智度論 (dàzhì dù lùn, Mahāprajñāpāramitāśāstra), attributed to Nāgārjuna, and the Summa Theologica of Thomas Aquinas, this communication will present approximations in the interreligious dialogue between maitrī and amor amicitiae, as principles that transform the actions of Buddhist and Christian practitioners in society.