The Red Sox activated Mead following Sunday's 6-1 win over Toronto.
After being acquired from the Nationals earlier Sunday, Mead will be available to make his team debut Monday against the Athletics in Sacramento. The 25-year-old is expected to work primarily at second base with his new squad, even though he made just one of his 62 starts with Washington at that position. Mead had enjoyed a breakout campaign with the Nationals, posting a career-high .254 average with 17 home runs, 48 RBI, 49 runs scored and six stolen bases over 87 contests. Boston optioned infielder Tsung-Che Cheng to Triple-A Worcester to clear room on the 26-man active roster for Mead.