A letter featuring the signatures of numerous top Hollywood performers and creators urging the entertainment industry to be more inclusive of performers with disabilities has permeated throughout show business, and there's no sign of letting up.

“The entertainment industry has made strides in prioritizing diversity,” the letter, obtained by Deadline on Friday, said. “At the 2019 Academy Awards, diversity and related topics such as race, immigration, and sexual orientation were explicitly mentioned on stage 38 times.”

The letter has already been signed by the likes of Norman Lear, Glenn Close, Danny DeVito, Jason Alexander, Mark Ruffalo and many others, and is being circulated by the Ruderman Family Foundation, a leading organization spearheading disability inclusion that has been instrumental in sounding the alarm on shows and films that cast able-bodied performers in disabled roles.

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“We applaud the industry for elevating these issues to the world’s largest and most glamorous stage. But in the history of the Academy Awards, among the 61 Oscar nominees and 27 winners playing characters with a disability, only two were authentically portrayed by an actor with disability,” the letter continued.

"Therefore, we must ask: Why is disability excluded from the diversity conversation? Twenty-percent of the world’s population has some type of visible or invisible disability, making this community the largest minority in the world. Yet people with disabilities are systematically excluded from opportunities for social and economic mobility," it said.

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"Now is the time to change the conversation. Hollywood can play a significant role in driving socioeconomic progress for people with disabilities. The entertainment industry must embrace disability as a key facet of diversity and can help normalize disability, erasing the stigma that surrounds it," the letter said.

"While many beloved characters have a disability, opportunities for actors with disabilities are virtually nonexistent. In fact, research shows that 95 percent of top show characters with disabilities on TV are played by actors without disabilities. Yet it is still the norm for able-bodied actors to play characters with disabilities," it added.

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In the manifesto, the Ruderman Foundation issues a call to action for industry big wigs and others to pledge to audition actors who have disabilities and cast qualified performers with disabilities, “thereby improving their visibility and expanding overall talent pools. Only then will the entertainment industry finally live up to its vast potential for leadership in diversity, inclusion, social justice and civil rights,” per the full letter.

According to Variety, the organization began certifying films and shows with its unique seal of approval for authentic representation. The outlet reported that, as of Friday, only 15 titles have garnered the seal so far.