Under what circumstances would a company be willing to hire an intern without an interview?

Most companies will interview, even if it by phone, any intern they are considering. It may be possible that a candidate who has attended an information session where the candidate has mingled with the employer, but not a personal interview, could be considered. As mentioned by Dmitri - if the candidate has been prescreened by a recruiter or referred by a trusted contact it is possible the company may extend an offer without first interviewing the candidate. If a representative of the company has seen the intern candidate in action, perhaps worked on a project together, observed their content or interactions in social media, seen any work product then they may feel comfortable with the persons ability to fill an internship role without an interview. What information would the employer require - if the candidate is not being referred by a trusted referee, and even if they are, once may need to submit a resume and letter of application, references, possibly work samples and references. Additionally, the candidate may indeed be asked to complete psychometric screening and/or skills and aptitude testing. An Intern, typically a student or recent graduate may also need to demonstrate academic success and relevance. This could include working with a noted professor on a relevant topic. The role and industry can be a factor in this situation. If the role involves primarily working on tasks where competency can be demonstrated in documentation and testing and where the role may be virtual or remote, you may find an organization more willing to bypass the formal interview process. Demonstrating interest and ability can often lead one to an opportunity that kind of emerges, we call that planned happenstance career planning. If you are positioning yourself well with your activities to demonstrate your abilities or interests others may find you or you may fall into an opportunity that bypasses the formal process. It does happen frequently. If you want to target an employer or industry may even be able to make this happen. You have to get out there and be noticed if you want to skip the formal process.