The feature film version of the Fox TV show was announced last year but fans were left concerned about its status after star Michael Cera described the project as "hypothetical".
Speaking to MTV News at Sunday night's Oscars, the sitcom's executive producer insisted that the movie is still happening and is gaining momentum.
"I had a great meeting with [series creator] Mitch [Hurwitz]. Things are going really well. He's writing," said Howard.
Discussing speculation that Cera (George Michael Bluth) is "holding out" on reprising his role, he added: "We've been asked to no longer divulge anything or get into the game of who's in, who's out. People are going to have to see."
Arrested Development aired on Fox from 2003 until 2006.