A rise in the number of students in the UK, including undergraduates from overseas, is likely to mean increased plagiarism, a report has said.
Colleges and universities are being sent guidelines written by experts in the higher education technology organisation, Jisc.
The authors say: "student plagiarism in the UK is common and is probably becoming more so".
This may reflect increased pressures, perhaps from taking on paid work.
The report, Deterring, Detecting and Dealing with Student Plagiarism, said:
"A decision to plagiarise may be associated with increasing pressures on students arising from, for example, undertaking paid work, heavier coursework load, or lack of personal organisation skills.
"When stresses rise, students see plagiarism as a reasonable and reasonably risk-free way out of difficulties."
A minority did it deliberately.
"We can only guess as to the frequency of behaviours such as paying ghost writers, wholesale downloading of coursework, or copying from other students", it said.
Evidence was building up through the increased use of detection software.
But the report said: "Many studies show that the bulk of plagiarism can be attributed to students who do not understand academic requirements."
It often involved "top-up" programmes with high numbers of international students who did the first two years in their home country then finished the degree in the UK, often submitting a dissertation after just eight months of UK study.
Some academics felt it was more frequent in distance-learning programmes, or more common in very large classes.
"If these students enter programmes where the 'rules of the game' are unclear, they might continue to use tried and tested approaches and thereby, inadvertently, plagiarise," the report said.
"The number of students falling into this category will grow as student cohorts become more diverse due to widening participation, increasing numbers of international students and greater use of different teaching modes (e.g. distance learning, work-based learning)."
So the guidelines argue that deterrence will always be more effective than detection.
A "holistic" approach is needed which establishes "underlying cultures and beliefs", "placing academic issues at the centre of the discussions".
The principal author, Jude Carroll of Oxford Brookes University, said: "These guidelines matter because unless people have confidence in the relevance, reliability and effectiveness of policies and procedures, they won't use them and without good procedures and reliable policies, all the other efforts we make will be less effective.
"Although much emphasis is put on detection, policies are needed to deal effectively with the cases we already detect and do little about."
Deterring, Detecting and Dealing with Student Plagiarism, Joint Information Systems Committee.