Purity Balls, probably better termed "galas," are an effort on the part of predominately evangelical Christians to promote sexual abstinence in the lives of the young women in their families. Young women attend these galas usually with their fathers, sometimes with a brother, uncle, or another male role model in their lives. The purpose? To pledge to remain pure until they marry. As you might suspect, a lot of people find these galas, at best, meaningless, and at worst, the father's attempt to own their daughter's sexuality and her body.
From Generations of Light:
The Father Daughter Purity Ball is a memorable ceremony for fathers to sign commitments to be responsible men of integrity in all areas of purity. The commitment also includes their vow to protect their daughters in their choices for purity. The daughters silently commit to live pure lives before God through the symbol of laying down a white rose at the cross. Because we cherish our daughters as regal princesses—for 1 Peter 3:4 says they are “precious in the sight of God”—we want to treat them as royalty.
While the silent commitment is on the part of the young women participating in the gala, this pledge is give by the father:
I, (DAUGHTER'S NAME)'S FATHER, CHOOSE BEFORE GOD TO COVER MY DAUGHTER AS HER AUTHORITY AND PROTECTION IN THE AREA OF PURITY. I WILL BE PURE IN MY OWN LIFE AS A MAN, HUSBAND AND FATHER. I WILL BE A MAN OF INTEGRITY AND ACCOUNTABLITY AS I LEAD, GUIDE AND PRAY OVER MY DAUGHTER AND MY FAMILY AS THE HIGH PRIEST IN MY HOME. THIS COVERING WILL BE USED BY GOD TO INFLUENCE GENERATIONS TO COME.
From this, I don't see that these young ladies are pledging their purity to their fathers, but committing a precious part of their lives to God. One of the questions posed to me was, do the purity balls/galas work? My response is that in many cases, it won't, but many times what works is not necessarily helpful. What's right is not always the easiest thing to do or accept. Some of the criticism of the purity movement relates to the teaching of abstinence, and it is my belief that we are foolish not to teach abstinence. Not to teach abstinence because abstinence doesn't work is like saying we shouldn't teach long division because everyone owns calculators.
Nothing about the purity movement concerns me except any attempt to turn it into a commercial enterprise. The interviewer shared with me that one of the products marketed to the young women in the movement is underwear that says "my daddy is watching." That's a bit much. But the movement is, in general, a positive promotion of what is truly good and beautiful.