'Developments in American politics' is a good collection of essays from a variety of authors who share their knowledge and expertise on this fascinating subject. This is in it's 6th edition now and is still as applicable as when I first used it. This book is a great introduction to American Politics. I bought my copy when doing my A-levels and I still refer back to it now to clarify points, or just to dip into out of general interest. The style is easy to read and the explanations and essays are clear. It covers all the major topics you would wish to look at in your studies and is a great references book for anyone interested in politics. Well worth a look. I also recommend 'American Politics and Society' by David McKay which has similar information but presented in a more traditional textbook format.