The paper describes, compares and analyses the main determinants associated with the high reading literacy achievement of Finnish and Swedish students by exploiting the PISA (OECD Programme for International Student Assessment) data collected in 2000 from the representative samples of the 15-year-old students in both countries. The initial results of PISA indicated that Finnish and Swedish students were among the best performing in all OECD countries. The students' proficiency was described in terms of five levels of reading literacy. The students in the highest proficiency level are capable of completing sophisticated reading tasks, such as retrieving, interpreting, reflecting and evaluating information embedded in long and complex texts from lists, tables and graphs to expository prose, arguments and narratives. In the OECD countries combined, 10 per cent of students achieved the highest proficiency level. In Finland, 18 per cent and in Sweden 11 per cent reached this level. This paper explores and compares by a means of logistic regression models the effects of various factors associated with high achievement in reading literacy. In previous studies (Elley 1994; Lundberg & Linnakyls 1994; OECD 2000; OECD 2001; Purves & Elley 1994; Taube 1988), a number of factors have been consistently identified as important in explaining reading literacy performance. Generally, variables indicating students' socio- demographic and home background, students' own interests and activities as well as learning strategies and attitudes have been found significant in explaining their proficiency in reading literacy. In the present study, we focus on exploring the explanation of excellence in reading literacy by comparing and contrasting high proficiency with average achievement. To estimate and to compare the effects of various determinants within the two national data sets, the stage-wise, two-level logistic regression models are exploited. In these regression models, the effects of several explanatory variables were estimated simultaneously in order to identify the factors with statistically significant effects on reading literacy while controlling the impacts of all other variables. Main questions addressed in the empirical analyses were as follows: á Which factors have the strongest effects on excellence in reading literacy? á Are the factors and effects the same among the Finnish and Swedish high achievers; and what are the similarities and differences? These questions are significant for the enhancement of learning environments and pedagogy for excellence in reading literacy. The preliminary results obtained through the logistic regression models indicate that in both countries, among the socio-demographic factors, the female gender and the native competence of language have the most significant positive effects on high literacy proficiency. From the home background factors, both the parents' high educational attainment and high socio-economic status were significant supporting elements as were also the cultural communication and the number of books at home. On the contrary, active social communication at home had a negative association with high literacy achievement. Students' own interests and activities had a strong - even stronger than their home background - impact on students' achievement in both countries. Students' engagement in reading activities and enjoyment of reading fiction were significant explanators. Likewise, students' learning strategies and activities at school had some effect. Particularly, positive academic and language-bound self- esteem, good disciplinary climate and strong personal effort supported high reading proficiency. Instead, memorisation and co-operative strategies had a negative effect for high achievement. The similarities and differences of the two national models will be compared and discussed from the perspective of enhancing reading literacy learning environments.