Yes, COMMUNALISM is a Scrabble word!

Letter values in Scrabble US: C 3, O 1, M 3, M 3, U 1, N 1, A 1, L 1, I 1, S 1, M 3.

Is it a valid word?

COMMUNALISM is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

the practice of communal living and common ownership
loyalty and commitment to the interests of your own minority or ethnic group rather than to society as a whole