If you're a “Jack of All Trades” who signed up for every club in school, you may win the prize for most memberships but you won't be winning the hearts of any admissions officers.
Fact: Colleges are looking for well-rounded, committed students.
Think about your track record for extracurricular activities:
Do you rock at one or two activities?
Or
Do you flop around from club to club spending the minimum time possible in each?
As you build your college resume, think about how you are going to truthfully demonstrate that you are well-rounded (engaged inside and outside the classroom) and committed (dedicated to these outside pursuits). Colleges want to see that you have well-developed interests and the ability to make and reach goals.
My advice: Pick a manageable number of activities (less than three, for most of us) and devote your time to being the best that you can be. Show steady progress toward a defined goal, such as a leadership position or a higher standing on a sports team.
Remember, your core academics are still the primary focus when you apply. Extracurricular successes aside, you must demonstrate that you have what it takes to graduate successfully.