“Enough” depends on what your son is interested in and how much academic work/EC time he can manage without becoming over-stressed. Debate was an ideal EC for our son; it honed his critical thinking skills, taught him to analyze both sides of issues, and made him a very comfortable, articulate presenter which has served him well in college. I can’t imagine any other EC that would have been better for him. The time commitment, combined with a rigorous academic load, was significant. He had little time for other EC’s beyond a school play. Ultimately, your son’s interests should guide his choices…don’t try to push him into a particular EC based on what you think colleges may want.