Dedicated to the mission of improving the quality of human life, The YMCA of San Diego County supports the community through youth development, healthy living and social responsibility. The nonprofit is San Diego’s seventh largest employer and the second largest YMCA in the United States.Dedicated to the mission of improving the quality of human life, The YMCA of San Diego County supports the community through youth development, healthy living and social responsibility. The nonprofit is San Diego’s seventh largest employer and the second largest YMCA in the United States.