Kendrick Sampson, Tessa Thompson, and Black Lives Matter have joined forces to challenge Hollywood’s commitment to change in an open letter that’s already been signed by over 300 of the industry’s finest.

Black Lives Matter co-founder Patrisse Cullors, BLM Los Angeles Chapter co-founder Melina Abdullah and “Westworld” actress Tessa Thompson also were part of the development of the letter.

“Due to Hollywood’s immense influence over politics and culture, all of the racism, discrimination, and glass ceilings Black people in Hollywood experience on a regular basis have direct implications on Black lives everywhere,” the letter reads.

The letter, which calls out Hollywood’s “lack of a true commitment to inclusion and institutional support,” delves into the lack of control and influence that Black people have in the industry — in front of and especially behind the camera, where the majority of the important decisions are made.

“Every time a Black executive or assistant is passed over for a promotion, or the marketing or production budget for another Black-led film is limited, or when Black agents aren’t supported, Black writers are shut out, outnumbered or diminished, Black hairstylists are neglected, Black grips, gaffers, and camera assistants and operators are shut out of below the line unions – EVERY SINGLE TIME – this gives us less control over our narratives, continues the legacy of white supremacy’s influence over our stories and makes Black people in Hollywood and all over America less safe.”