The Salesian Sisters dedicate themselves to the teachings of Don Bosco, a 19th century Roman Catholic priest who spent his life educating disadvantaged youth. Joining with Maria Domenica Mazzarello in 1872, he founded the Daughters of Mary Help of Christians, a sister organization to his order, the Salesians. Numbering over 15,000 worldwide, women take vows of "poverty, chastity, and obedience to God". They work as missionaries, teachers, and caregivers for young people. Upon joining the Salesian sisters, nuns renew their vows every year for 6 years. On the 7th year, they take a final vow committing themselves to their vocation for life.