ABC's are written agreements between a young person, the local housing office or Registered Social Landlord (RSL), and the local police in which the person agrees not to carry out a series of identifiable behaviors that have been defined as antisocial. The contracts are aimed at young people between ages 10 to 18 years. The findings are based on a range of qualitative and quantitative data that include police and housing data for 95 children placed on the ABC scheme in the London Borough of Islington between 1999 and 2001; and background data from education welfare officers and schools in Islington. The results showed that fewer of the young people came to the attention of the police and housing officers for antisocial behavior for the first 6 months of the contract. The overall number of antisocial acts committed by young people also decreased while on contract. Some young people that had committed criminal offenses in the 6 months prior to the contract continued to do so but at a reduced rate. Forty-three percent of the contracts were breached. A total of 80 antisocial acts were committed by young people while on contract. There was a wide range in the number of times contracts were breached -- 57 percent of contracts were not breached; 19 percent were breached once; 12 percent were breached twice; and a further 12 percent were breached at least three times. Police and housing officers were not always aware that contracts had been breached and there were some concerns that contracts were not enforced. Recommendations for improving the way that ABC's are implemented include sharing protocols with relevant agencies; standardizing the way that data are recorded; informing the community about the scheme; and ensuring that there is adequate monitoring and feedback. 22 tables, 1 figure, 32 references