Most of the literature reviewed is U.S. based: little or no comparable research on ABE participation and ABE attrition has been undertaken in Canada. The literature has been survey-oriented in the past, but in the 1980s several researchers have conducted theory-based and empirical studies in attempts to provide firmer theoretical foundations or conceptual frameworks examination of ABE phenomena. The complex nature of the target population, however, presents many difficulties to researchers as some of the results of reviewed studies have shown.

What has emerged from the literature review is a strong emphasis on the heterogeneity of target population. Undereducated adults cannot be viewed as a homogeneous population simply requiring 'more education'. A variety of psychological and socio-demographic variables interact with the learning setting to produce many different effects. The various typologies that have been developed of low-literate adults confirm the heterogeneity of the target population. implications for practice are to consider differentiated recruitment efforts and program design in order to serve the target population more effectively.

Much of the literature in the U.S. has been directed at adult high school noncompleters or those involved in GED programs. The average grade level attained by most of the population samples appears to be around the ninth grade level. There is an emphasis also on traditional ABE, that is, classroom-based instruction within institutions. The race variable is also evident in U.S. ABE research studies: Black, White and Hispanic factors are often considered and sometimes figure in results.

The contradictory nature and inconclusiveness of the findings of many of the studies call replication efforts in other ABE circumstances and with different samples. Such replication is called for by the researchers themselves. ABE research is still in its infancy. Much more needs to done, not only in replicating existing ABE studies and experimenting with new conceptual frameworks for ABE, but also in coming to consensus on such crucial terms as "dropout" and "persister". If every researcher defines these terms differently, useful comparisons will always be difficult to make.

Qualitative aspects and effects in ABE literacy programs cannot be ignored. The studies of self-planned learning projects among low-literate adults and preliminary work on resisters of ABE show that many adults are capable and willing to learn - but not in a traditional educational setting. Many researchers see the community-based approach as one answer for a certain segment of the target population. Whatever the approach, adult educators must recognize the social background and specific learning needs of low-literate adults. In the words of Fingeret (1983), "if we do not learn to work with them, many illiterate adults will continue to refuse to work with us" (p. 144).