By Alex Kirby
BBC News Online environment correspondent
Trying to improve the lives of children in a poor Latin American community by channelling money to their mothers has achieved good results, economists say.
Violence is endemic in the region
The initiative gives mothers in small Colombian towns and villages money for improving their children's food intake.
In return, younger children have to go for regular medical check-ups and older ones have to attend school regularly.
The Institute for Fiscal Studies says early results show more children going to school and enjoying improved diets.
The institute investigated the initiative to see how financial institutions should target funds to alleviate poverty and promote development.
Carrots but no sticks
The programme, inspired by similar initiatives in Mexico, began in 2002, funded by the World Bank and the Inter-American Development Bank.
It aims to enable the poorest families to feed their children better, and to encourage parents to send them to school for longer.
In return for cash payments, which are meant to be spent on food, mothers of under-fives are asked to take the children for regular medical check-ups and vaccinations.
Mothers themselves are required to attend classes on hygiene, vaccination and contraception.
Mothers of children aged from six to 17 receive payments if their children attend school regularly.
With Colombian colleagues IFS is evaluating the programme's results, comparing the 50 towns and villages where it is being tried with 50 control areas where it is not.
Conflict is widespread in the region: every one of the 70 interviewers involved was held at gunpoint by guerrillas at least once.
Extreme poverty is commonplace as well: families have on average less than $1 a day to spend on each member, 10% of children suffer from severe malnutrition, 13% from diarrhoea and 42% from respiratory disease of some kind.
IFS says the preliminary results of the survey suggest the programme is working:
One of the authors of the IFS report, Professor Orazio Attanasio, said: "This evaluation is important, not just for Colombia, but to help us understand how developing countries can best target valuable resources to improve the prospects for their poorest children."
- older children's school enrolment rates rose, by 13% in towns and 5.5% in rural areas
- the number of times urban children ate meat rose from two to three times weekly, and the number of times they ate vegetables more than doubled
- the changes in diet seemed to be helping children to gain weight - by an average of 2.5% in rural areas.