Yes, PROACTIVE is a Scrabble word!

Letter values in Scrabble US: P 3, R 1, O 1, A 1, C 3, T 1, I 1, V 4, E 1.

Is it a valid word?

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

descriptive of any event or stimulus or process that has an effect on events or stimuli or processes that occur subsequently
(of a policy or person or action) controlling a situation by causing something to happen rather than waiting to respond to it after it happens