You are hereRecommended Reading
Q - "What books do you recommend to learn Thai?"
A - The answer will all depend on your purpose for studying Thai. I will try to outline some typical reasons here for you.
1. ALG was designed for real language acquisition. We don't use, nor recommend books at all, as authentic language cannot be gained from books. Once an ALG student is able to speak somewhat, we then used books for teaching reading and writing.
2. You already have a working knowledge of Thai, (i.e. able to communicate verbally and understand what is said to you) and you want to develop in reading and writing.
3. You want to pass a test or exam. In this case, the books I would recommend are dependent on the exam and your individual needs.
4. You plan to spend some time in Thailand and want to develop a basic working knowledge of the language. I would find any book that would give me about 10 words or short phrases, memorize these, and then stop. It can be very gratifying to use a little "Thai" but realize that learning in this way is never a basis for authentic language, and it is limited by your ability to remember details about language.