President Obama Sworn in for Second Term President Barack Obama and Vice President Joe Biden today officially embarked on their second term, taking the Constitutionally mandated oath of office in two separate private ceremonies inside their homes. Shortly before noon in the Blue Room of the White House, Obama raised his right hand, with his left on a family Bible, reciting the oath administrated by Chief Justice John Roberts. He was surrounded by immediate family members, including first lady Michelle Obama and daughters, Malia and Sasha. "I did it," he said to his daughters after taking the oath. Biden was sworn in earlier today by Justice Sonia Sotomayor, the first Hispanic to administer a presidential oath, in a ceremony at his official residence at the U.S. Naval Observatory. He was joined by more than 120 guests, including cabinet members, extended family and his wife, Dr. Jill Biden. Because Jan. 20 -- the official date for a new presidential term -- falls on a Sunday this year, organizers delayed by one day the traditional public inauguration ceremony and parade down Pennsylvania Avenue. Obama and Biden will each repeat the oath on Monday on the west front of the Capitol, surrounded by hundreds of dignitaries and members of Congress. An estimated 800,000 people are expected to gather on the National Mall to witness the moment and inaugural parade to follow. The dual ceremonies in 2013 means Obama will become the second president in U.S. history to take the presidential oath four times. He was sworn in twice in 2008 out of an abundance of caution after Roberts flubbed the oath of office during the public administration. This year Roberts read from a script. Franklin Roosevelt was also sworn in four times but, unlike Obama, he was elected four times. Both Obama and Biden took the oath using a special family Bible. Obama used a text that belonged to Michelle Obama's grandmother LaVaughn Delores Robinson. Biden placed his hand on a 120-year-old book with a Celtic cross on the cover that has been passed down through Biden clan. The official inaugural activities today also included moments of prayer and remembrance that marked the solemnity of the day. Obama and Biden met at Arlington National Cemetery for a brief morning ceremony to place a wreath on the Tomb of the Unknowns, honoring military service members who served and sacrificed. The men stood shoulder to shoulder, bowing their heads as a bugler played "Taps." Biden, who is Catholic, began the day with a private family mass at his residence. The president and first family attended church services at Metropolitan African Methodist Episcopal Church, a historically black church and site of two pre-inaugural prayer services for former President Bill Clinton and Vice President Al Gore and their families. The Obamas and Bidens plan to participate in a church service on Monday morning at St. John's Episcopal, across Lafayette Park from the White House. They will also attend a National Prayer Service on Tuesday at the National Cathedral. Later on Sunday evening, the newly-inaugurated leaders will attend a candlelight reception at the National Building Museum. The president and vice president are expected to deliver brief remarks to their supporters. The official inaugural weekend festivities began Saturday in Washington with a National Day of Service led by Obama and the first lady. The Obamas joined volunteers at a local D.C. elementary school, where they helped with rennovation projects. Organizers said thousands of Americans participated in service events in conjunction with the inauguration across all 50 states. More than 13,000 people attended a so-called Service Summit on the National Mall. Michelle Obama and Jill Biden also hosted a Kids Inaugural ball Saturday, carrying on a tradition started in 2009. The event was geared toward children of military families as part of Obama's "Joining Forces" initiative. A concert included performances by Usher, the cast of "Glee," and Katy Perry. The stars will be out in force across Washington again on Monday, with performances at the inaugural cermony at the Capitol and at the official inaugural balls later in the evening. At the ceremony, BeyoncÃ© will sing the National Anthem, Kelly Clarkson will perform "My Country 'Tis of Thee," and James Taylor will sing "America the Beautiful." The stars scheduled to perform at the various balls include Marc Anthony, Jennifer Hudson, Alicia Keys, John Legend, Stevie Wonder, and Smokey Robinson. Officials have not yet revealed who will perform for the president and first lady's inaugural dance.