[header] How to teach your kitten to be calm and relaxed [title] Pick the right age. [step] Kittens are most easily socialized between the ages of two to seven weeks. This means that the kitten is more likely to accept new animals, peoples, and situations during this age range. 
Although most respectable mother cat owners won't separate the kittens from the mother until the age of eight weeks, this falls outside of the proper time frame. This means that it is typically the original owner's job to socialize the kittens while she is still with the litter and her mother.