Being multi-lingual has no academic advantage, an Australian study of 5000 children has found.
The research conducted by academics at Charles Sturt University and the Queensland University of Technology found speaking a language other than English did not affect children's academic outcomes at school. 
"The report shows that there is no advantage or disadvantage to speaking multiple languages in terms of school readiness, literacy or numeracy," said one of the authors, Sharynne McLeod.
According to the Australian Bureau of Statistics, 23 per cent of the population speaks a second language at home, with Mandarin, Italian and Arabic the most popular languages.
The report is the culmination of five years of research through the Longitudinal Study of Australian Children [LSAC] and a $686,400 grant awarded through the Future Fellowships research council.
The teachers reported the outcomes of their students between four and nine years old using a variety of measures including the academic rating scale, language and literacy scale and the mathematical thinking scale.
Professor McLeod and Linda Harrison from CSU's Research Institute for Professional Practice, Learning and Education along with with Dr Chrystal Whiteford and Sue Walker from QUT found that five-year-old multilingual children actually had poorer English receptive vocabulary and more behaviour problems than their English-only peers.
By the time these children had reached nine years old this gap had closed.
Children with typical speech and language development, both multilingual and English-only, achieved similar and higher academic ratings.
Professor McLeod said that while parents in metropolitan areas were more likely to believe multilingualism was an advantage, during the course of their research they found large parts of regional Australia thought it was better to only teach their children English.
"A mother stood up during a meeting in Port Macquarie and said that her and her husband spoke two different Indian languages and were concerned that their child wouldn't grasp English if they spoke it to him at home," said Professor McLeod.
She urged those with multiple languages at home to not be discouraged from teaching them to their children.
"It will not delay their development or impact on their academic outcomes," she said.
"Understanding other cultures and languages and how they work can only be of benefit. Increasing tolerance and learning other things is a really wonderful way to understanding of the world."
She said that if parents were concerned about the speech development, regardless of the language of their children, they should take action early.
Children with speech and language concerns in their early childhood years, regardless of their multilingual status, received poorer academic ratings for literacy and numeracy, the study found.
"A four to five-year-old's speech should be intelligible most of the time. Ask yourself, when they speak to strangers do they understand them?
"That means that their speech is at a level that is going to be ready for the literacy demands of school."