Investors tend to get wary when smaller companies seek faster growth by expanding beyond their core industry competency through repeated acquisitions.

But Wall Street generally applauded earlier this month when health care staffing specialist On Assignment Inc. said that it was buying Oxford Global Resources, a Beverly, Mass.-based national staffing company specializing in information technology and engineering. It was the Calabasas-based company’s second acquisition in as many months.

On Assignment’s shares have risen more than 8 percent since the deal was announced Jan. 3, closing at $12.74 on Jan. 10. Analysts say that was in large part because management carefully laid the groundwork for the acquisition, and had a track record of turning around what had been a faltering company only a few years ago.

Jeffrey Silber, an analyst with BMI Capital Markets Corp., said that in addition to the usual conference call, Chief Executive Peter Dameris held meetings with key investors to walk them through the deal. Among the points made: both Dameris and other key members of his team have IT industry experience, Dameris as chief executive of a global IT staffing firm he had sold for $1.9 billion.

“If the executives had not known anything about IT I’d be a little bit nervous,” Silber said. “But I actually used to cover the company that Peter ran in the ’90s. He had started out there in business development he was their M & A; guy so this is kind of in his DNA on two levels.”

For his own part, Dameris believes Oxford has a compatible corporate culture