The cross-country evidence points to four distinct country profiles, differentiated by the prevalence, depth and nature of low foundational skills, each with its own policy logic. In near-threshold countries (Canada, Czechia, Croatia, Estonia, Hungary, Ireland, Italy, Japan, Korea, Lithuania, Poland, Slovak Republic, Spain, Sweden) the population of adults with low foundational skills is clustered just below medium proficiency and relatively homogeneous. The distance to travel is short, and well-targeted short-course upskilling is a viable primary lever. In deep deficit countries, the population is, on average, further from medium proficiency and more internally diverse (Chile, Denmark, Finland, the Flemish Region (Belgium), France, Germany, Israel, the Netherlands, Portugal). Chile faces both high prevalence and deep deficits; Finland, paradoxically, belongs to the same group, not because the problem is widespread, but because the small population with low skills faces severe disadvantage. In both cases, provision must be intensive, long-duration, and inseparable from a broader educational equity agenda.
Literacy gap countries - Austria, Latvia, Norway, Singapore and Switzerland - face what is in large part a language integration challenge. Rapid and sustained language acquisition support for newly arrived migrants and language minorities is the highest-return investment available. Numeracy gap countries, including England, New Zealand and the United States, face a different kind of challenge, one that appears to originate upstream in the quality and equity of compulsory mathematics education. Remedial adult provision can help at the margins, but no adult learning system can fully compensate for what initial schooling failed to deliver.
Independent of country profile, prevention is key. High-quality early childhood education and care is the highest long-run return investment available to most governments, particularly for children from disadvantaged families. Breaking the intergenerational transmission of low skills requires both reaching adults today and ensuring the next generation enters schooling with the preparation to succeed.