First of all, you are not alone! It may seem like everyone else is comfortable in social situations, but this is not true. In one study of 1,000 people, 40 percent said they were shy to the point of it being a problem.
Social anxiety disorder is the fourth most common mental health disorder after depression, alcohol abuse, and specific phobias.
The hallmark of shyness is the fear of being scrutinized or negatively judged by others in social situations. Shy people are afraid of saying or doing something that will embarrass or humiliate them. Anticipating these feared situations provokes anxiety in the shy person, and how you handle this anxiety is how we determine if you are simply shy or if you have social anxiety disorder.
If you are avoiding social situations to the point where it is interfering significantly with your work, school, social activities, or relationships you are likely suffering from social anxiety disorder.
Genetics play a big role in both shyness and social anxiety disorder. You are two to three times more likely to have social anxiety disorder if you have a parent or sibling with it. The disorder affects males and females equally, and it is very unusual to develop it in adulthood; the typical age of onset is between 11and 19 years old.
Cognitive-behavioral therapy, or CBT, is an effective treatment for social anxiety disorder. CBT is based on the relationship between thoughts, feelings, and behaviors. Let’s take a typical situation, where you’d like to engage in conversation with a coworker but you find yourself avoiding situations where a conversation might happen. It’s true that by avoiding you may feel less anxious, but you do not get to test if your anxious thoughts are accurate, and you don’t get to practice small talk. So avoidance works in the short run, but not in the long run. (See diagram below.)
As with all anxiety disorders, people overestimate the threat—and social anxiety disorder is no exception. A CBT therapist will usually begin by helping you identify of the threatening thought you are having. “I won’t know what to say. There will be awkward silences and my coworker will think I am boring and stupid.”
How accurate is that thought? While it’s true that if you engage in a conversation with your co-worker, there may be an awkward silence. But everyone experiences this at times, and it does not usually lead to rejection.
The “B” in CBT stands for behavioral change—helping people to face their fears. We call this exposure therapy, which is done in small and manageable steps, like climbing a ladder. A typical first exposure might be simply to smile and say hi to a coworker. Subsequent exposures may be asking a question, sharing one thing about your weekend, and eventually, having a three-minute conversation.
Shyness itself is not bad. In fact, shy people are often sensitive, thoughtful, and good at understanding others. It is important not to let your shyness stop you from doing what you want to do, like meeting people, making friends, dating, and speaking in front of groups.
People who have social anxiety have an underlying belief that they need to be socially perfect: no awkward silences, no signs of anxiety, and never tripping over their words, forgetting names, and always sounding smart and interesting. I call this social perfectionism, and no one can meet this standard. This is what I tell my clients all the time:
• Lower the bar for yourself.
• Be willing to make mistakes because everyone else does.
Once you develop more realistic expectations for yourself, it becomes a little easier to face your fears and live the life you want.
Ms. Shannon, a licensed marriage and family therapist, is the cofounder and clinical director of the Santa Rosa Center for Cognitive-Behavioral Therapy. 
The Shyness and Social Anxiety Workbook for Teens: CBT and ACT Skills to Help Build Social Confidence,  by Jennifer Shannon, LMFT (Instant Help Books, New Harbinger, 2012)
Podcast:  Teen Social Anxiety Disorder: Cognitive-Behavioral Interventions That Work
Video: Ms. Shannon's daughter, Rose, speaks about her social anxiety as a teen and how cognitive-behavioral therapy (CBT) helped her.