By Jeff Horwitz
Former top Facebook Inc. deputy Chris Cox is returning to the social-media giant, just over a year after leaving amid disagreements with CEO Mark Zuckerberg over the company's direction.
Mr. Cox, who was one of Facebook's earliest engineers, announced his plans to return as the company's head of product, the job he resigned in March 2019. The core of the role is executing Mr. Zuckerberg's vision for Facebook's platforms, and Mr. Cox was known to have disagreed with the chief executive's plans to move toward unifying the company's products around encrypted messaging and other topics.
Mr. Cox, 37 years old, told people that he worried that the shift to encryption would impede detection of such criminal activity as terrorism and child trafficking, The Wall Street Journal reported in April.
Mr. Cox also championed a push within Facebook to examine its culpability in spreading misinformation and divisive content in the years before he left, work that the company deprioritized, the Journal reported last month.
It isn't clear if the men have resolved their disagreements, but Mr. Cox said in his return announcement that he has been "encouraged by progress on so many of the big issues facing us."
Mr. Cox, who spent part of his time away from the company working on progressive causes, could help shore up Mr. Zuckerberg's support among some employees who have expressed frustration with Facebook's policies regarding political speech and specifically the platform's hands-off approach to President Trump.
Also on Thursday, Facebook expanded the role of chief diversity officer Maxine Williams, who will now report to Chief Operating Officer Sheryl Sandberg.
In a Facebook post announcing his move, Mr. Cox said discussions about his return began about a month ago when he reached out to Mr. Zuckerberg. After spending more than a year with his family, supporting political causes and playing with his reggae band, Mr. Cox said, he felt called to return. According to the post, that will be on June 22.
"2020 refocused us all, on a public health crisis, an economic crisis, and now a reckoning of racial injustice. The world is unsettled, divided. People are struggling when things were already hard," he wrote, calling Facebook "the best place for me to roll up my sleeves and dig in to help."
Mr. Cox will oversee the company's largest products: Facebook, Instagram, WhatsApp and Messenger. In addition to guiding the development of new features, the role requires Mr. Cox to help address the unforeseen problems arising from existing products. In response to vitriol and misinformation on Facebook during the 2016 campaign, he championed an approach to products that examined the impact of the company on society rather than just growth.
"For people who want to see Facebook succeed, this is Christmas morning, " said Donald Graham, a former Facebook board member who has known Mr. Cox for years. "Chris's return is the best news I could imagine for the company."
Facebook has been roiled by employee protests, including a walkout and resignations by a handful of staffers, over its handling of content moderation issues and President Trump's use of its platform.
Since leaving Facebook, Mr. Cox told people that he was going to focus on climate change and progressive politics. The header on his personal Facebook page features a Black Lives Matter stamp.
Last year he donated money to Acronym, a Democratic digital firm, according to people familiar with the matter. At a conference last year, Mr. Cox told an audience that he wanted Mr. Trump out of office, but still defended the company's hands-off approach to the president on the platform.
"I think when you're in a very senior role at a platform, you have a duty to be much more neutral in your politics," he said.
Deepa Seetharaman contributed to this article.
Write to Jeff Horwitz at Jeff.Horwitz@wsj.com