"Having said that, the big challenges that Singh faces are all too clear. India's neighbourhood is witnessing political instablity, with developments in Pakistan and Afghanistan along with political uncertainty in Sri Lanka and Nepal as well."
Pranab Mukherjee, the foreign minister, AK Antony, the defence minister, and Palaniappan Chidambaram, the interior minister, were among the few who took the oath of office at the ceremony.
A statement issued by the prime minister's office said that several more were to be swoen in on Tuesday in a second ceremony.
The delay was to allow the Congress time to complete coalition negotiations with some of its allies.
"The first task is to restore the economy and its growth momentum," Singh said after the ceremony.
During his second term, Singh will have to decide how much to prioritise reforms such as labour laws and privatisations over pressure to spend more on social programmes that helped Congress win the election.
Vijay Dutt, the UK bureau chief for The Hindustan Times, told Al Jazeera: "As far as the recession is concerned, I think Singh is better placed than before. The blockade caused by the left will no longer be there so he can push for economic reform much faster.
"Singh is a very able economist and he has the assistance of people who know exactly how to meet global recession challenges and keep up to pace with modernisation trends in a global economy."
The Indian elections, the world's largest democratic exercise, was marked by a turnout of 428 million people.
Singh, 76, a former economist, was thrust into the position of prime minister in 2004 when Sonia Gandhi, the Congress chairman, declined the position and picked him.