Ask eHop: Unenrolled voters in the primary?

Ask eHop: How can unenrolled voters participate in the primary election? 

Massachusetts has open primaries, meaning registered independent, or unenrolled, voters can decide whether to vote in the Republican, Democratic or Green-Rainbow primary. Read more in the Hopkinton Crier. 22% of Hopkinton voters are Democrats, 20% are Republican, and 57% are unenrolled.