"It gives the kids some good work experience, gives them some responsibility and gets them to understand how business works."
One physiotherapy business employed senior high school students to staff its reception desk after school hours, he said.
Part-time work for students was a good idea provided their hours were "not too excessive".
Menial work was better for a younger age group, but work which required more responsibility such as answering phones or handling cash was better left to 16 or 17-year-olds.
Secondary Principals' Association president Tom Parsons said a part-time job was not always a positive move for a student.
"Many of the kids that do the part-time work, do the part-time work not to put butter on the bread, but to put bread in the house."
Secondary school students were not allowed to do paid work during school hours.
"Principals like myself have enforced this before where kids have been caught - sometimes at the parents' behest - trying to leave school early [for work] or come late because they've slept in because they've been working until 10 or 11 o'clock at night.
But it's pretty rare."
Most parents recognised children needed education to get a good job later in life, rather than cutting school for a part-time job.
The Dunedin study, which appears in the Journal of Adolescent Health, tracked the participants up to age 32.
Of the study's participants, just over 5 per cent had part-time jobs at age 11, while 26 per cent and 42 per cent worked at ages 13 and 15, respectively.
The study's lead author, Dr Ella Iosua, said participants who had part-time jobs between ages 11 and 15 years were not more likely to suffer negative outcomes in psychological well-being or academic qualifications by age 32.
Part-time work did not make them more likely to smoke, to drink alcohol excessively, nor regularly use cannabis as adults.
The study findings supported the Government's position that children were adequately protected by legislation, she said. "Our findings can help provide reassurance that moderate part-time work is unlikely to be detrimental in countries like New Zealand."
However, she cautioned that might not apply to long hours or unsafe working conditions in societies with less protection.