BBC World Affairs correspondent Mark Doyle, who was in Liberia for the post-war United Nations-backed elections, gives this analysis of the difficulties ahead for Africa's first elected woman president.
Mrs Johnson-Sirleaf is an experienced diplomat and politician
To get a measure of the challenges facing the President-elect of Liberia, Ellen Johnson-Sirleaf, who has just been declared the winner of Liberian elections, you need look no further than the official residence of the Head of State, currently occupied by the outgoing interim leader.
By international standards it is a modest, even rather scruffy ocean-front house behind high walls. If it were in, say, Nigeria or almost any other African state, you would think it belonged to a medium-level trader or a local politician.
In Monrovia, the only thing that obviously singles the place out as the official presidential residence is the presence at the gates of black-suited Liberian security men and United Nations peacekeepers.
The road leading to the residence is potholed. Within spitting distance of the gates, there are rough shanty homes made of tin roofing sheets and clapboard.
Children who should be at school carry water up and down the road in plastic jerry cans, and, within sight of the residence, there are piles of rotting rubbish.
Crumbling infrastructure and a lack of running water are of course endemic in Africa. But it is a measure of Liberia's plight that even the head of state lives so near to such squalor.
The problems facing Liberia's incoming president do not include a lack of resources.
A relatively small country with a population of just three million, Liberia has the potential to be a middle income country. Its land is criss-crossed by rivers watering fertile soil that supports rubber, palm oil and tropical fruit plantations.
It has some of the richest timber resources anywhere in Africa; mountains bearing some of the world's highest quality iron ore; and significant deposits of diamonds and gold.
But Liberia's resources have never been rationally exploited.
Shortly after the country became Africa's first modern republic in 1848, when it was settled by freed slaves from the United States, huge plantations were marked out by the black settlers and foreign investors.
Paying little attention to the needs of the indigenous population, these farms and plantations made a few people very rich but dispossessed many more.
Widespread resentment built up between the black colonialists, who had formed a sort of elite oligarchy in the capital, and their impoverished indigenous black cousins in the rural areas.
Installing piped water in the capital is one of many competing needs
That resentment exploded in 1980 when a young army Master Sergeant, an indigenous Liberian, Samuel Doe, seized power in a bloody coup d'etat.
The country has been suffering the consequences ever since. Liberia descended into a cycle of coup and counter coup, war and repression.
This conflict favoured the worst sort of buccaneer business practices and simple criminality across the country - illegal logging, illegal mining and straightforward stealing from government ministries became commonplace. At a lower level, petty thieving was rife.
The cycle of instability was only interrupted two years ago when the United Nations began deploying a large peacekeeping force to police a peace agreement which was made possible by the departure for exile - under pressure from the United States - of the pre-eminent warlord for almost a decade, Charles Taylor.
But while the UN - which still has the biggest guns in town - can keep the peace, Mrs Johnson-Sirleaf will have to tackle the corruption.
This will be far from easy because it has permeated political as well as business circles.
An energetic 67-year-old grandmother, Mrs Johnson-Sirleaf has excellent international credentials. Trained as an economist at the prestigious Harvard University in the US, she has worked as an international banker and as a manager for the United Nations.
She is not tainted by the corruption allegations that follow most Liberian politicians.
But while Mrs Johnson Sirleaf will have no trouble holding her own with fellow presidents and international diplomats, the domestic political challenge she faces is perhaps more significant.
The first political bridge that has to be built is with her opponent in the run-off race, the retired soccer star George Weah.
She has said she will offer him a job in her new administration; whether he will accept, while he continues to make allegations of ballot rigging against his campaign, is not yet clear.
There will be plenty of other domestic challenges as Mrs Johnson-Sirleaf tries to implement economic policies designed to boost employment, increase educational provision and build basic clinics and hospitals.
The biggest problem is probably unemployment. Currently, hundreds of thousands of young men are condemned to scratching a living by petty trading or day-labouring.
Historically, this has made them easy prey to be manipulated by warlords or dishonest politicians.
The vested interests of many powerful Liberians would be challenged by honest government. If that's what Ellen Johnson Sirleaf intends to introduce, she has a bumpy ride ahead.