According to the UNICEF state of the World's Children Report of 2006;

Street children are among the most physically visible of all children, living and working on the roads and public squares of cities all over the world. Yet, paradoxically, they are also among the most 'invisible' and therefore hardest children to reach with vital services such as education and health-care, and the most difficult to protect.

The exact number of street children is impossible to quantify, but it is likely to number in the tens of millions or higher, some estimates place the figure as high as 100 million. It is likely that the numbers are increasing as the global population grows and as urbanization continues apace: 6 out of 10 urban dwellers are expected to be under 18 years of age by 2005.

In practice, every city in the world has some street children, including the biggest and richest cities of the industrialized world. Most street children are not orphans. Many are still in contact with their families and work on the streets to augment the household income. Many others have run away from home, often in response to psychological, physical or sexual abuse. The majority are male, as girls seem to endure abusive or exploitative situations at home for longer - though once they do leave their home and family, girls are generally less likely to return.

Once on the street, children become vulnerable to all forms of exploitation and abuse and their daily lives are likely to be far removed from the childhood envisioned in the Convention on the Rights of the Child. In some cases, those who are entrusted to protect them become the perpetrators of crimes against them. Street children have been harassed or beaten by police and often find themselves in conflict with the law. Some have been rounded up, driven outside city limits and left there. Other have been murdered by vigilantes in the name of 'cleaning up the city', often with the complicity or disregard of local authorities.