This book was very helpful in correcting my Spanish grammar errors. The grammatical explanations and examples are clear. The "blunders" are clearly indicated in red ink and with a red check mark. Each chapter includes a brief exercise for assessing the extent to which concepts were learned (with answers at the appendix at the end of the book). Although most of the book dealt with grammar, I found the section on vocabulary building helpful as well. As I went through this book I was surprised at the extent to which I inappropriately applied English grammatical concepts to Spanish.