Do I have to volunteer a lot during high school? I know some kids who have more than 1000 volunteer hours. I might have close to 100 hours. Will the schools I apply to care about the differences?

I only had 150 hours of volunteer work. I think that it is important to remember that the college admission process is not based on some formula. Most colleges look at your application in a holistic manner. Not everyone is public service oriented or community service minded. It is more important to be involved in things that interest you.

I have around 150 hours as well. I worked with blind people last summer and it was a great experience for me.

I had around 400, but that's only because I liked to occupy myself during the summers in high school and during the year. I genuinely liked volunteering at the places I was at so it wasn't really work to me. At least 100 hours seems like a decent number, admissions people won't be that impressed with how many hours you do as you would think.

Would the type of work you volunteer for make a difference though? Would it be more impressive to have volunteered in a well-known organization for 50 hours, than a smaller more private organization for 100?

I believe it's mainly about the level of difficulty to get in and longevity. A well known organization can just be an organization specializing in youth volunteerism, therefore not proving to be a challenge to get in. Whereas getting a volunteer job at a private organization can be more competitive and difficult. It really doesn't matter if an organization is public, well-known or private. Obviously getting a volunteer job at McDonalds isn't as impressing as getting a volunteer job at the Haus of GaGa, even though McDonalds is more well-known. As for the amount of time volunteered, colleges favor commitment so a greater amount of hours at one place would be ideal.