Almost all freshmen choose to live on-campus because of the convenience and safety of campus housing. Penn has a system of college houses and each house fosters a very warm 
and welcoming sense of community. The most popular freshman houses are the three houses in the Quad, (Fisher Hassenfeld, Riepe, and Ware), Hill College House, and Kings Court English House. The other college houses are Stouffer, Gregory, W. E. B. Dubois, Harnwell, Rodin, and Harrison. With the exception of Rodin, freshmen are accepted in all of the college houses. Each college house also offers residential programs (for instance, the International Program in Harnwell and the Law and Society program in Fisher Hassenfeld) which freshmen can apply to if they want to live with people who have similar interests as indicated by the type of residential program. The housing application is available online on Campus Express in late April/early May.
Note: An important factor to consider in your decision is that all the College Houses with the exception of the high rises (Harnwell, Harrison, and Rodin) and Sansom Place East and West are closed over Winter Break. If you live in one of the low rises and expect to stay in the US over winter break, you will need to find a host to stay with for the duration of the break.