Pop quiz. How old do you have to be to join LinkedIn? The answer is 16. High School and College Students are welcome members of the LinkedIn community. Which means it's never too early for young adults to learn about building a network of professional contacts. Mary Wu is self-employed as a Social Media Consultant, working predominantly with coaches and consultants. In addition, she’s passionate about mentoring 16-24 year olds about using “LinkedIn for Life” to acquire the skills needed for their career success.