Parents of children often ask whether their children are withdrawn and do not like to communicate with others, and worry whether their children are pathological and need treatment. We will not discuss the reasons for the child’s withdrawn personality because they are complex and may be related to family, society and the influence of our country’s past one-child policy. We will only talk about whether or not a child’s withdrawn personality is a mental illness. In psychiatric practice, there are two main criteria for diagnosing whether a disease is pathological: first, whether the individual’s behavior deviates significantly from the norm, including comparison with most people of the same age and the individual’s consistent behavior in the past; and second, whether the individual feels internal pain or seriously affects social functioning, which includes learning, work, interpersonal communication and other aspects. Only when both of these conditions are met can a diagnosis of a mental illness be made, but the social functioning criteria are more important. For example, a child with a peculiar personality and exceptional intelligence, whose behavior pattern is significantly different from that of children of the same age, but who is not suffering internally and who is able to learn and interact normally, cannot be considered mentally ill, as has been the case with many gifted people throughout history. On the other hand, we can sometimes see individuals who do not behave in a particular way, but are unable to go to school or work and stay at home most of the day doing nothing, which we call impaired social functioning. According to the above principle, for children who are withdrawn and do not like to talk, if they can go to school normally and can maintain basic social interaction, we consider them to be in a “low-functioning state”, which means that although the level of social functioning is low, but not without social function, it cannot be easily considered pathological at this time. At this point, parents may ask, if it is not pathological, then is it not necessary to take care of it? An article published in 2013 in a leading international academic mental health journal titled “Teacher-assessed deficits in student social functioning may predict the onset of adult mental illness” reads as follows: Deficits in social functioning are a core component of mental illness and occur prior to the onset of mental illness. This study examined the relationship between social functioning deficits and mental illness in children. The results suggest that there is a strong association between teacher-assessed impaired social functioning in students and future mental illness and that social functioning deficits can also be a psychological stressor for children. The teacher used a simple scale to assess the following five areas: 1. he/she rarely participates in fun activities when other students do; 2. he/she has no friends; 3. he/she is often teased; 4. he/she does not actively seek out friends; and 5. he/she always seems to avoid contact with other students. So the results of this study tell us that children who grow up with a lack of social skills will also grow up to be less socially competent and may be more susceptible to mental illness as a result. The lack of social skills is mainly manifested in the following areas: 1. decreased facial expression of emotion; 2. no interest in social activities; 3. decreased speech; 4. no interest in social interaction; 5. low verbal response; 6. inflexible eyes; 7. reticence; 8. imitation of speech; and 9. changing topics. According to the above diagnostic criteria and research findings, as a parent, if you find that your child is withdrawn, I think you should pay attention to two points: first, do not be anxious, because being withdrawn is not equal to mental illness; second, you should pay attention to your child’s social problems and find ways to help your child improve his or her social skills in life. Of course, how to help children improve their social skills is also a complex issue that requires the family, the school and the children themselves to work together, constantly summarize their experiences and methods, and eventually obtain improvements.