Too Shy!

Welcome to the forum, feeling sorry for your dog's behavior actually is nurturing that behavior, so you can stop doing that to help him []

Second you can start working on the shy part by doing this, have a friend coming over, tell the friend to completly ignore your dog, sit down in the living room and tell your friend to hold a treat in his hand, the swettest the better, tell your friend to just hold the treat down and talk to you in the mean time, let the dog to take his time to come closer and take the treat for himself, is really important that you and your friend act like if the dog is not there, he will start thinking that strangers are a good thing since they always "bring" food, the key is not talking to him, no touch and no eye contact

Your dog is shy, but it could be also about low self esteem, by petting the dog they are also nurturing the behavior, they are saying "is ok to feel that way, keep doing it", i know that your puppy is really cute but that would cause more trouble than help right now

Here is a link from a professional that talks about dogs being afraid of humans:

http://www.dogpsychologycenter.com/blog/Season2ep02.php

And this one about low self esteem:

http://www.dogpsychologycenter.com/blog/Season2ep06.php

I hope it helps []

How are they petting him, and what breed is he? It could be the way they are approaching him makes him feel intimidated, particularly if he is small.

What espencer suggested is a great way to build confidence:

Second you can start working on the shy part by doing this, have a friend coming over, tell the friend to completly ignore your dog, sit down in the living room and tell your friend to hold a treat in his hand, the swettest the better, tell your friend to just hold the treat down and talk to you in the mean time, let the dog to take his time to come closer and take the treat for himself...

Probably the main reason he's shy is that he spent his crucial socialization period in the shelter and did not get enough exposure to new people. Because that period from 8-16 weeks is so influential on the dog's personality and outlook for the rest of his life, he may never be the outgoing social dog that perhaps he had the potential to be. But you can help him come out of his shell a little.
 
This link explains the socialization window pretty well: [linkhttp://miniatureschnauzer.ca/socialization.htm]http://miniatureschnauzer.ca/socialization.htm[/link]
 
The first thing is to respect his point of view and try to persuade other people to do the same. So don't be embarrassed, and don't let people come on to him too strong in an attempt to 'make' him be more friendly. Having your friends give him treats is a great idea, but let him come to them. You could even just have him watch people toss the treats onto the floor, if approaching is too scary for him at first. Continue to give him opportunities to have good experiences with new people & places, but just be aware of his comfort zone. If he's stressed and wants to leave, he can leave.
 
Because of his early deprivation in life, things that 'should' be ordinary to your pup are new and strange and seem otentially dangerous. Imagine that you grew up deep in the countryside where you saw your family and two neighbors and no television for the first 16 years of your life... and then one day your family sends you to NYC with a bus pass and you're on your own. That's my vision of what an unsocialized puppy goes through as he grows up.

Thank all of you for advice. Yesterday I pushed my puppy close to my friends and had him stay there to improve his socialization although he seemed to want to escape. Now it turned out the bad remedy...[8D] Sorry for him. I will try espencer's suggestion next time we have guests.

My puppy is mixed, but I am not sure what kind of mixed. The shelter told me he was a cockapoo before adoption (I just saw him at petfinder.com), but when I went there to pick him up, I found out he is not. Some people said he looks like a french sheepdog or dutch sheepdog...but who knows? []

Wish me a luck with my puppy's socialization. Will keep you posted if there is any improvement.

He's adorable! I'm sure in a little time he'll be more confident. If guests can excuse the bashful young toddler ("Oh, he's just shy") then I'm sure they'll understand your pup's social awkwardness as well. Maybe for a while start with one guest at a time, if you can, and kind of work up from there so it's not quite so intimidating for him?

Don't shove your pup toward guests.  And, don't have them lean over him, stare at him, or reach their hands out.  Instead, tell him "say hello" in a cheery voice and let the guest toss a treat (one that is smelly, and easily seen) onto the floor in front of him.  Or, if that seems too much, and he still shies away, or freezes, just let the guest hold a treat down at his side.  If the dog approaches and takes it, fine.  If not, fine.  Let the dog go to the humans in his own time.  Fear can turn to aggression sometimes, so don't push him beyond his limits, even if he has not exhibited this tendency, and may never.  If he is the only dog in the home, you can even make a "food trail" toward the guests, but don't have them interact with him. 
You can do some exercises to help dogs boost their own confidence levels (it will never be the same as a dog that was properly socialized, but some dogs do get better, if only just a bit).
Two books that can help:
"The Cautious Canine" - Patricia McConnell
"Help for Your Shy Dog" -  Deborah Wood
As your dog's leader, your job is to let him use you as a base of support by not making a big deal of the approach of strangers (which might suggest that you are afraid, too, LOL), and not to coddle fear (so you must resist the temptation to tell him "aw, it's ok").

Thank you, spiritdogs! I won't shove my puppy toward guest any more. []
 
I will check the libraries if they have the books you recommended.

They may not - but you can get them at [linkhttp://www.dogwise.com]www.dogwise.com[/link] or amazon probably.
Trish McConnell's books are all here:
[linkhttp://www.dogsbestfriendtraining.com]www.dogsbestfriendtraining.com[/link]

Also, Google on "puppy stages of development" so you can understand why your pup missed out on some valuable lessons between the ages of 10-15 weeks.  It'll help you be more patient when teaching him. []