Awww I'll bet that little face is hard to resist!! They will DEFINITELY pull at your heartstrings, but it is super important never to reward or give in to him crying; as doing so just rewards him for fussing; hence you would be basically training him TO fuss/scream/cry which is the opposite of what you want. You simply have to be diligent; and ignore him (no words of comfort, no trying to soothe from afar, no "It's okay, I'm still here!"'s from the other room. In order for him to actually learn to self-soothe, it's paramount that he be given the opportunity. He will learn in due time, and it's important that he does, should you ever be in any emergency situation where he needs to be left alone or crated for any amount of time. Chihuahuas are brilliant, albeit VERY manipulative, dogs if given the chance to be so; which is why it's important for you as the owner to set boundaries for him and help him learn what is okay and what is just plain obnoxious. =) Make sure his crate is somewhere that he can't see you when he's inside of it; you can cover it with a blanket; put a clock or radio overtop for some background noise; and I even use a drop of lavender on the top of the crate each night for the one puppy I am crate training for his new owner. He's almost 3 months old, and now only cries on and off for about 5 minutes before drifting off to sleep because he's learning that there really is no point to him whining, because never once have we "given in," to his cries. I wish you the best of luck!!