Give this a try, http://www.eslmonkeys.com/teacher/books/free_esl_book.php

Hope it helps! y Buena Suerte!

When you are choosing an ESL grammar book, it will depend on the level of the English language learner (ELL). An ESL beginner will need a different book than an advanced ESL student.

The age of the ELL also needs to be taken into consideration. ESL grammar books for children (and here I would agree with Dudley J that grammar books may be a waste of time) will be different than those for adults.

It also depends on whether you are the teacher or the student. Are you looking for a grammar book that will just answer your questions when you're unsure of some grammar point, or do you need a book with exercises?

I use a few different ESL grammar books for some of my students.

Here's a list of the books I use regularly:

Practical English Usage
Understanding and Using English Grammar
Grammar in UseIntermediate
Basic Grammar in Use

There is more detailed information about each of these books at http://www.teaching-esl-to-adults.com/esl-textbook-evaluation.html

Studying grammar is a waste of time. Children don't learn to speak a language that way, and you shouldn't either. Fire your teacher.