Technology has a diversity problem. The shortage of women and minorities in STEM fields including computer science and engineering is well known. As a result, it's difficult to have a diverse workforce. That doesn't mean it's not possible; it just means diversity won't happen on its own—you need to work at it. Make sure diversity is addressed by every step of your hiring pipeline.
Look for Candidates in the Right Places
If you look for candidates in just one place, you're likely to find just one kind of candidate. Widen your net to find a bigger, more diverse pool of potential employees. For example, don't limit yourself to elite universities; graduates of second tier schools aren't second rate. And while there are definite advantages to hiring based on employee referrals, those candidates are likely to be similar to the employee who referred them.
Write Job Descriptions That Appeal to a Wide Community
No one writes job descriptions today that say they're looking for a man, but the language you use can unintentionally turn off women. So avoid describing the job by making analogies to the military or sports teams; even terms like rockstar developer can drive away diverse applicants. Think carefully about word choices; to build a team, lead a team, or manage a team can all attract a different applicant pool. Even the way the job description is formatted can have an impact, with high or low numbers of bullet points driving away male or female applicants.
Make Sure Technical Screenings Focus on Technical Skills
While you want to evaluate all candidates' interpersonal, communication, and leadership skills, don't mingle that evaluation with the technical interview. Conduct a separate assessment that focuses solely on technical ability to avoid any impact from unconscious biases. For coding tasks, ask the candidate to solve them on the computer. This ensures they can solve the problem in a situation close to the real work environment; some candidates are uncomfortable working at a whiteboard, which isn't a requirement when building technical solutions once hired.