The source said Best will be able to take part in the Detroit's OTAs, minicamps and training camp. While Best hasn't been cleared to return to football yet, the source would be "shocked" if Best isn't able to fully participate.
Best suffered his latest concussion on Oct. 16, when the Lions lost to San Francisco, and was placed on injured reserve in November.
Best also missed time during this preseason because of a concussion, and when he was a college player at California, he missed a few games after a fall knocked him out and sent him to the hospital with a concussion and sore back.
The Lions drafted Best in the first round in 2010. He ran for 555 yards as a rookie last season and caught 58 passes despite toe problems.
He started the first six games of this season, running for 390 yards on 84 carries. Lions coach Jim Schwartz said he started experiencing "concussion-like symptoms" after the loss to San Francisco.
Adam Schefter is an NFL Insider for ESPN. Information from The Associated Press contributed to this report.