The paper shows a strong language policy can reduce barriers to trade, improve student performance across the curriculum, and influence better health and well-being, particularly among Maori, Pacific and migrant groups.
The costs of a monolingual society were high, such as reduced international trade, weaker integration of immigrants, and the potential decline or loss of indigenous languages.
Royal Society vice-president of the social sciences and humanities Richard Le Heron said the research outlined a strong case for a national languages policy in New Zealand.
Australia's languages policy is nearly 20 years old and its government is pushing for more access to Asian languages in schools.
Britain was considering making every English-speaking child learn a second language from age 7.
In New Zealand, a Labour-led 1992 languages policy discussion paper, "Aoteareo: speaking for ourselves", was dropped by the next National-led government.
Language learning is not mandatory at any level in New Zealand.
An education policy introduced in 2002 placed more emphasis on learning Asian, Pacific and European languages, but this has faded. More primary and intermediate students were studying languages compared with 2000, but fewer secondary school students were learning a language.
Education Minister Hekia Parata's office said that the number of students learning Japanese and Chinese had climbed over the past five years, and the ministry had developed services to support Pacific languages from early childhood centres to high schools.
There was no immediate plan for a shakeup of the education sector's approach to languages.
Dr Harvey said a good first step in a national-level policy would be to focus on Te Reo Maori and Pacific languages, but also encourage Asian language learning with an eye to improved trade connections.
Labour MP Phil Goff felt that New Zealand had a responsibility not only for the Maori language but the Pacific languages spoken by our neighbours.
"For small countries, the majority of their population reside in New Zealand. Letting a language, and therefore a culture, become extinct would be unforgivable."
His Mt Roskill electorate was the most diverse in New Zealand. When he attended the opening of an ANZ bank branch last week, the staff spoke eight languages between them.
Mr Goff, who spoke "one and a quarter languages", was concerned immigrants had no encouragement to maintain their mother tongue.
Linguistic diversity in New Zealand as a distribution of the average number of languages spoken per person. For example, if a region has an average number of languages spoken per person of 1.5 or greater, one out of two people will be bilingual or multilingual (Area unit data from Statistics NZ, Census 2006, Credits: Dr Paul Behrens, Dr Paul Murrell).