Irish children are less likely to smoke cigarettes, drink alcohol or take cannabis than in the late 1990s, a study found.
Nine out of 10 youngsters also revealed they were happy with life in 2010, but almost a quarter still felt low at least once a week.
The Health Behaviour in School-aged Children (HBSC) Ireland survey was carried out by the Health Promotion Research Centre in NUI Galway.
It found 12% of Irish children were smoking in 2010 compared to 21% in 1998.
Another 28% reported they had been drunk, down from 29%, and 8% admitted to using cannabis, a fall from 10%.
Health Minister James Reilly said he was encouraged by the drop in numbers.
"This is a step in the right direction and I hope to see this continue for the good of all our children," he said.
"As Minister for Health I have placed a high priority in highlighting the deadly dangers of smoking, in particular, for our children and I will continue that battle."
Data relating to almost 40,000 children was collected and examined between 1998 and 2010.
Researchers said t he percentage of young people living with both their mother and father fell from 91.4% to 73.7% during that period.
The numbers who admitted they had bullied others two or more times in the past couple of months also dropped from a quarter to 16.4%.
And m ore than half said they talked to their friends on the phone, via text messages or on the internet every day, while four out of 10 feel pressured by schoolwork.
Healthwise, a fifth of children said they ate fruit more than once a day and half said they exercised four or more time per week, a fall from 54%
Of the 12% that smoked almost half had started by the age of 13 or younger, compared to 61% in 1998.
About 13% were on a diet while a third said their health was excellent, 91% of children were happy and 76% reported high life satisfaction, all up on previous years.
Elsewhere seat-belt wearing rates have doubled to 82%.
Principal Investigator Dr Saoirse Nic Gabhainn said: "This report is the culmination of many years of work, and brings some good news about the health behaviours of children in Ireland over the years, with a decrease in smoking and in alcohol use for example.
"Yet still more needs to be done to improve their health, in particular around physical activity.
"Importantly, the proportion of children reporting high life satisfaction and being happy, fundamental aspects of childhood, has increased over the years, as have health and safety behaviours such as wearing a seatbelt and brushing teeth."