A £224 million database holding information on every child in England has been launched in a bid to make sure authorities are alerted as quickly as possible when a child is at risk.
ContactPoint will contain the name, address, date of birth, GP and school of all under-18s - along with contact details of social workers or any other professional involved with the child.
The directory was created in response to the Laming Inquiry into the tragic death of eight-year-old Victoria Climbie in 2000, but concerns over data security and technical issues meant the project suffered several delays.
Civil liberties groups, children's campaigners and the Office of the Information Commissioner have all expressed concerns about its scope and role, but the government says no case information will be held on ContactPoint and it will be impossible to download its contents.
Children's secretary, Ed Balls, said it would help those who work with children, including police and health professionals, to "prevent problems escalating". As seen in recent cases, a lack of "proper and timely information sharing" could have tragic consequences, he said.
"The risks to children from such a register outweigh the benefits. Why can't professionals communicate to each other and be responsible for updating each other when children move out or are identified as new children moving in?" - P Aseervatham, London
"Being an ex-health visitor I would have welcomed this database as an essential tool for tracing lost families quickly. I am all for early prevention and detection but as yet not fully convinced this resource will prevent the terrible tragedies of Baby P and others. Perhaps once I have read and absorbed more regarding the database purpose I might have differing views." - V Henry
"While I fully understand the requirements for professionals to have access to information in order to safeguard children, on a personal level I am gravely concerned that my children's infomation is to be held yet again on another computerised list. I am not convinced by reassurances that information is confidential, protected and inaccessible to the general public. As we know information is not safe, as proven in recent losses of personal information on laptops of army personnel containing national insurance details of thousands of people. This is yet another example of "big brother" and I find it abhorent that I cannot prevent my children's information from being included." - Angela Goode, Cumbria