I have read a lot of books on screenwriting - some very helpful, others not so much. I believe they're good for learning about all the technical aspects such as how to create characters, writing the synopsis, the treatment, an outline, the script itself. But the ones that I have benefited from the most were actually three of this four-book list - I haven't read Poetics in its entirety yet. I also really like David Mamet's On Directing Film - it's a rather short book but worth the read. I read Blink of an Eye only six months ago but it immediately reached my Top 10. I'm also very favorable to Jennifer Van Sijll's Cinematic Screenwriting which is probably more for directors/editors but a writer can still benefit from all the visual ideas it presents. Screenwriting books are good if they're read as a complement or used as a creative spark. I used to go through a couple of pages on character in Karl Iglesias' Writing for Emotional Impact before digging in. What I have benefited from the most, though, is reading scripts. One a week for the past ten years, more if I'm prepping a story and wish to see how others have done in the same genre (not too many, though, so as not to become involuntarily influenced). Anyone seeking general advice or who is curious about how it works for the pros would probably enjoy 101 Habits of Highly Successful Screenwriters or Tales from the Script. Yes, I'm an avid reader, always have been since childhood :)

I saw this question on Twitter yesterday, was gonna chime in but this is a better platform. I too have read quite a few screenwriting books. Not an insane amount but enough to satisfy my craving. My advise for anybody who wants to read screenwriting books is this: Do your research, find a few that have great reviews or that people you trust recommend (like Scott above), read them, take notes and be done with it. Because here's what inevitably happens: You start reading the same thing, over and over and over. It gets really old really fast, especially when you could be spending your free time reading other stuff that might inspire your more creative side. Honestly, if you're someone who want to learn the craft, all you could ever want is on this site. I think Scott's said there's something like 17,000 posts here. That's absolutely insane. Whatever the subject, you can probably find article upon article about it at GITS. As Scott also states all the time, you have to be careful about the information you digest. Yes, it's important to read as much as you can about screenwriting, but if you're not conscious of what you're doing you could turn into a system robot where all your ideas and thoughts and strategy stem from the concept of what works and has worked for decades in Hollywood. I think in today's market you really have to give people something new. Black List readers are tired of the ever-willing protagonist who follows the Hero's Journey and gets the girl in the end. Of course you can write an original script that includes these elements and is still novel. But why? Why not try something new? Why not take what you've learned and be confident that you can write a compelling story with complicated characters and nail-biting suspense that flips your genre on its head? That's the real challenge. If you're able to craft a great story that breaks all the rules rather than follows them ardently, that's your surefire ticket to the next level.

I agree, this site is a great resource. But I didn't find it until I'd already taken several courses and studied a dozen or so books, including Goldman. I got something out of almost all of them. It didn't matter that one author's feature list is as thin as the paper this comment is written on. Or that one book is largely based on an earlier work. They were all worth reading--except for one that started well, then ended in a different voice, feebly. Screenwriting is organic. So is learning. Reading the same concept several times is a way to really grasp it at the deepest, most instinctive levels. The writer's brain is no less complex than any movie. Late last year, I took a course in acting to give me the actor's POV. I'm not through learning yet, but the writing moves on.