We just finished basic training and I was lucky, the instructor has both big dogs and a papillon (sp) so she knew about various types of harnesses. I really learned alot in class, myself. The instructor really limited it 5 mos and younger but made an exception for us since Hot Rod was only 2.4 lbs at 6 mos. I enjoyed the class and I think Hot Rod did too...I made him salmon for his training treat. He did great in class and I was so proud of him. We did have 2 problems, the instructor finally took the lead of when we were working with him since he was so small, it was like an anchor on him for some of the exercises. The other, since Hot Rod was older, we'd been working with him at home with the basics-sit, down, stay, etc., so he already knew some things...he was scared by the clicker. After a while the instructor said not to use since it seem to make him nervous and anxious. But overall, I can say I am glad we took the classes.