Puritans thought the Church of England simply couldn't be reformed to their liking. They also lived in fear of persecution. Decided to come to America.
Instability: Henry wanting divorce and breaking away, Mary wanted Calvinism, etc.
Plymouth was a much healthier environment; more people migrated there and it grew more quickly than the Chesapeake area.
Very focused on cohesive family. Adoption was a thing--didn't want outcasts in society.