"My OG [email protected]_parkhas slayed my heart over and over again since our secret life of the american teenager days with her creativity + ability to see through the masks we all wear in order to absorb the full human experience," Woodley wrote. "But, she has taken that slay to a whole new level with @the_fallout_movie. ... the ENTIRE cast give this film such a moving and entrancing truth with their work."

She continued, "It's no secret to any of us the effects irresponsible gun use + violence has on our society especially on young people trying to live their best lives in public schools. megan has written + directed a movie that will touch your SOUL and have you thinking about it for days, months, years later."

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Megan Park and Shailene Woodley Credit: David Livingston/Getty Images; Stefania D'Alessandro/Getty Images

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"I'm so proud of you dude," said Woodley. "I couldn't be more inspired by the way you so uniquely use your force to tell stories that not only MATTER, but also that are told in innovative, beautiful, honest, and real ways."

With The Fallout, Woodley said viewers should "be prepared to have your heart melt + contract + expand + implode + explode all at once."

"I'm not sure i've ever seen a more honest portrayal of what our youth experience today both the pulses of their inner worlds + the textures that make up their outer experiences," she wrote.

"@megan_parkthe ultimate babe. my forever muse. just don't let it get to your head," joked Woodley. "even though you're a 1000000000000000000000/1 writer/director/creator now, don't think our kitchen musical karaoke parties are over."

Shailene Woodley and Megan Park Shailene Woodley and Megan Park in 2009 | Credit: Kevin Mazur/WireImage

Park, 35, sweetly responded to the Big Little Lies star in the comment section.

"I am so grateful for you. Thank you for coming to play and being so supportive and inspiring. I love you," she wrote. "Since I met you in those keds at 15, from kitchen Karaoke to holding hands and sobbing through several Broadway shows can't wait to keep being inspired and creating together forever. Ily ily ily."

Woodley further celebrated the project on her Instagram Story, writing that 19-year-old Ortega "gives one of the best performances i've ever seen in this film."

the fallout Credit: HBO Max/Twitter

"Jenna: you should be so proud. you are a marvel. working with you for a short couple hours was such a gift watching you pour truth through your heart is one of the most moving things to witness firsthand," said Woodley of the rising Yes Day and Scream actress. "i cant wait to continue watching how your career unfolds. you are a force to be reckoned with."

The Fallout, which also stars Julie Bowen, Niles Fitch, Will Ropp and John Ortiz, is available to stream Jan. 27 on HBO Max.