The full Mao quotation:

The situation of the Great Proletarian Cultural Revolution across the country is excellent, not just moderately good. The overall situation is better than ever before. A key indicator of this excellent situation is the full mobilization of the people. Never before has a mass movement been mobilized so extensively and deeply. — Mao Zedong

全国的无产阶级文化大革命形势大好,不是小好。整 个形势比以往任何时候都好。形势大好的重要标志,是人 民群众充分发动起来了。从来的群众运动都没有象这次发 动得这么广泛,这么深入。毛泽东

The image is a well-known artwork, also reproduced on PC-1967-023.

The Zhejiang Worker-Peasant-Soldier Art Academy is credited on the poster, the individual artists/designers are not mentioned.

Print no. 7150.895.