There are several causes of depression in teenagers. For instance, the main causes that teenagers may suffer from depression are academic stress, problems at home and at school. Causing the depression by financial struggles in family, having low self-esteem, lacking the ability to face the difficulties is possible (Kavya. vidyarthi., 2015). No doubt the academic stress will lead to depression suffered from teenagers. Compare with the pass, social competition have been more and more drastic. Teenagers are one of the victim of this society. There is a possibility that teens will be thought they are not competitive enough lead to feeling stressful. Moreover, the parents are having the greatest expectation of children’s’ achievement. The parents may want them to take part in several extra-curriculum class such as Mathematical Olympiad classes after school. They may feel stressful due to they don’t have enough resting time for recreation. Teens may suffer the depression as a result of problem at home. For instance, they may having divorcing parents. It will cause emotional disturbance of teens due to facing the dissolution family. Teens may feel depression while facing their parents are quarrelling with each other. Moreover, teenagers are on the rebellious period, who may ignore or argue with their parent lead to have conflicts and a bad relationship . These will cause stressful to the teenagers. Nowadays, parents are having long working hours and do not take initiative to care about their children or communicate with them. Teens will consider their emotion and feeling are neglected by their parents lead to feeling loneliness and neglected. In some extreme cases, teens may suffer from domestic violence lead to feel ashamed and become self-enclosed to protect themselves from harm.They may feel stressful due to they would not express their emotional and feel no one they can talk with and understand them. Teens may also have problem at school lead to suffer from depression. The targets of the abuse are tend to teenagers who are different to others. The act of the abuse are designed to induce the victims a sense of powerlessness and helplessness, who are forced to experience the painful stress and helpness that they cannot handle and ignore (Angela. O., 2010). Moreover, teens may not know how to avoid being bully. The bullies are based on the race, religious, physical disability and family background. There several shortcomings of teens being bully. For instance, there is a possibility that the teens will be engaged in self-annihilation behavior like drug abused or smoke. Low self-esteem is also a disadvantage of peer pressure owing to the alienation from the peers. They may think they are different from the others and cannot gain support from the peers. Those are the causes of depression in teenagers. It shown that it is a very serious problem in Hong Kong.