Phoenix recently appeared in a promotional video for suicide prevention organization To Write Love On Her Arms alongside Miley Cyrus and Liv Tyler.
TWLOHA is a non-profit organization aimed at finding help for people struggling with self-injury, addiction, depression and suicidal thoughts.
In the video, Cyrus shows Phoenix how to log onto www.twloha.com.
Once there, they vote for TWLOHA, getting a chance to win $1 million.
Cyrus also teaches Phoenix who Lady Gaga is, perhaps playing on the fact that Joaquin Phoenix was actually living under a rock for the past year.
TWLOHA founder, Jamie Tworkowski, also appears in the vid, explaining that Phoenix often has writing on his arms, which was actually inspired the name of the organization.