Michelle Obama's office said on Thursday it had opened a Twitter account, as the US first lady turned 49.
The account is @FLOTUS, the acronym for First Lady of the United States, and it will be administered by the first lady's staff.
Tweets penned by the first lady herself will bear her initials - mo.
As of midday on Thursday, the account had just over 16,000 followers. That compares to 2.64 million for @MichelleObama, which opened in January 2012 and was run by President Barack Obama's re-election campaign team.
Tweets from the @MichelleObama account have been infrequent since her husband won the election on November 6.
The first utterance Thursday from @FLOTUS urged followers to wish Mrs Obama a happy birthday.