I adopted a dog and need some training advise?

I recently adopted a dog from the Humane Society. He is a Siberian husky and Shepard mix and very intelligent. He was 8 months old when I adopted him and I have had him for 3 months. He is really well behaved and very easy to train. I have already taught him several basic commands and tricks but I have run into a problem. When I have him outside or around friends and family he will not come to me when I call him. I need some advice about how to train him to come every time I call him for his safety and so I can have more control over him in chaotic family gatherings. I don't like having to keep him on a leash in order to have him obey. Please help me so that I can help my dog. Thanks.