Facebook Messenger added the ability to stream live video, adding a feature enjoyed by fans of rival application Snapchat.
Instant Video lets people broadcast real-time video in Messenger text exchanges, according to a Facebook blog post.
"It's perfect for sharing quick moments with friends who aren't right by your side or making your conversations richer by seeing each other face-to-face when you are messaging," Facebook said of the Instant Video feature.
Instant video was available in the latest version of the Messenger application on mobile devices powered by Apple or Android software.
People using Messenger can tap on a video icon to begin sharing real-time video, with the sound turned off by default but easily turned on.
"Instant Video is a reflection of the ubiquity of video -- we simply expect to have that ability in real-time, all the time," Facebook said.
The feature also matches one offered in rival Snapchat, the vanishing message service that became a hit with teenagers and lets members share pictures and video clips.
In July, Facebook said the number of users of its Messenger application had topped one billion.
Facebook itself has more than 1.6 billion users, and WhatsApp, another messaging application acquired by Facebook for some $20 billion in 2014, also counts more than a billion users.
Other services in the Facebook "family" include Instagram, which more than 500 million people use to share images.
Facebook recently took direct aim at video-loving adolescents, and Snapchat, with the release of a new iPhone app that allows teens to watch clips about the lives of their classmates.
The app, called Lifestage, is available for anyone to download on iPhone, although seeing profiles of other users is reserved for those 21 years of age or younger.
The social network allows users to make video clips to describe likes, peeves, dance styles and other aspects of their character.
Those clips are woven together to serve as public profiles that can be viewed by other Lifestage members, provided they are young enough.
Last month, Instagram put its own spin on a key Snapchat feature by letting users post "Stories" that eventually vanish from the Facebook-owned photo-and video-sharing app.