The British Council said a "wholesale decline" in the study of foreign languages in schools and universities had impacted on the nation's ability to trade with non-English-speaking partners.
The report, entitled Language Rich Europe, was published ahead of a languages summit at Stirling University organised by the Scottish Government.
The event today is aimed at making progress on a Government commitment to encourage pupils to learn two languages in addition to their mother tongue.
The British Council report found that in 2001 almost all pupils in Scotland studied a language up to the fourth year of secondary education, but this figure had fallen to 67% by 2010.
It also highlighted financial pressure on language courses at universities and colleges, with departments and some courses under threat.
The report concludes: "Scottish employers tend to circumvent rather than address language skill needs by exporting only to Anglophone countries or those where they can easily find English speakers."
Lloyd Anderson, director of the British Council Scotland, said: "This report appears to confirm our fear that Scotland could be missing out on export opportunities if we simply expect everyone to speak English.
"Language learning is a vital component of being good global citizens and in an increasingly globalised and interconnected world, our young people and future workforce will be at a disadvantage if they lack language skills and cultural awareness."
Dr Alasdair Allan, the Minister for Learning, said the Government had set an ambitious target to increase the value of international exports by 50% by 2017.
"We are committed to reinvigorating language learning and helping more Scottish pupils learn a second language such as French, German, Spanish or Chinese in primary school," he said.
"These radical steps aim to increase the numbers of our children and young people gaining qualifications in languages, supporting them to be prepared and ready to flourish in the globalised, multilingual world we live in."
He added: "We will build on existing good practice across the country, with joined-up delivery between primary and secondary schools in developing local plans for implementation."
The Scottish Government has identified nine schools to explore ways of improving language learning, six of which will look at the introduction of languages from primary one.
The British Council report comes just months after a survey highlighted a sharp fall in the number of secondaries where a modern language is compulsory until S4.
Research by SCILT, Scotland's national centre for languages, also warned that many schools believe provision will decline further under the Curriculum for Excellence (CfE).
The survey by SCILT, based at Strathclyde University, found 39% of schools said pupils could drop languages at the end of S2 – even though CfE guidelines indicate pupils should stick with a language until the end of S3 at least.
The report states: "The compulsory status of modern language study in S4 had been removed in 51% of schools and there were fears, in some instances already realised, that this would be accelerated by the implementation of Curriculum for Excellence," it said.
Language Rich Europe is a consortium project led by the British Council and funded by the European Commission.