Rumspringa (from German 'running around') begins at 16. The teenager gains freedom: wear regular clothes, use a phone, attend parties, drive. Some move to the city.
Why
The Amish believe faith without choice isn't faith. A person must see the alternative and consciously choose the community. Baptism (permanent acceptance) happens only after Rumspringa — usually at 18–22.
What Happens
Most try a little: phones, movies, regular clothes. Some try more: alcohol, parties, city jobs. Very few go radical. Parents know and tolerate it — it's part of the system.
85% Return
The number has been stable for decades. Young Amish see the outside world and choose community. Not because they don't know the alternative — because they know it and prefer their own life.
Who Leaves
15% leave permanently. Community doesn't pursue, but contact is limited (Meidung — shunning). It's painful, but the Amish see it as the price of free choice.