Here are the lyrics from Norm Cohen's -American Folk Songs, Volume 1, pp. 263-264

WHICH SIDE ARE YOU ON?
(Florence Reese)

Come all of you poor (?) workers,
Good news to you I'll tell;
Of how that good old union
Has come in here to dwell.

CHORUS
Which side are you on?
Which side are you on?

We've started our good battle,
We know we're sure to win;
Because we've got the gun-thugs
A-lookin' very thin.

They say they have to guard us,
To educate their child;
Their children live in luxury,
Our children's almost wild.

With pistols and with rifles,
They take away our bread;
And if you miners hinted it,
They'd sock you on the head.

They say in Harlan County,
There are no neutrals there.
You either are a union man,
Or a thug for J.H. Blair.

Oh, workers can you stand it?
Oh, tell me how you can;
Will you be a lousy scab,
Or will you be a man?

My daddy was a miner,
He is now in the air and sun*;
He'll be with you fellow workers,
Until the battle's won.


Cohen's notes (part): In 1931, Florence Reece, wife of Sam Reece, a Harlan union organizer, wrote "Which Side Are You On?" to the tune of the Baptist hymn "Lay the Lily Low" after Sheriff J.H. Blair and his deputies broke into the Reece cabin and ransacked it, looking for Sam. It became one of the best-known songs to come out of Harlan's labor conflicts.

*Blacklisted and without a job.

There are almost identical lyrics (with fewer typos) on pp. 170-171 of John Greenway's American Folksongs of Protest (1953, University of Pennsylvania Press - 1960 Perpetua reprint). There is one major difference: the lyrics in Greenway begin:

Come all of you good workers