Fifty-four percent of large businesses that laid off employees in the past year are now having difficulty finding skilled workers. So to bridge the gap, many employers are considering rehiring former employees. Past employees who return to the fold are often called boomerangs. They’re more productive than novices because of their previous experience and institutional knowledge, and they tend to be more loyal after experiencing other work environments. In the hiring world, boomerangs are regarded as a pretty safe bet because they have a proven track record and can be sourced directly from alumni networks without a headhunting fee. Professional service firms have traditionally nurtured relationships with alumni, because they often refer business opportunities to their former firms. Now, consulting firms like Booz Allen Hamilton is refreshing its alumni group to build better relationships and identify possible return talent, according to senior associate Christopher Carlson. Naturally, companies are using social networks to stay in-touch with former employees but they’re also organizing face-to-face events and reunions. The latest online networks, often password-protected, can include message boards, blogs from executives, profiles of prominent alumni, and both internal and external job postings. But rehiring past employees may invoke resentment or jealousy from the current staff, and they may have bad attitudes or come with baggage from the past. The bottom line is look carefully before you hire a former worker, but boomerangs could be valuable resource going forward since the U.S. Labor Bureau projects a shortage of 1.5 million workers with bachelor’s degrees or higher by 2020.