This study investigated the cognitive (first language [L1] and foreign language [FL]), linguistic (L1 and FL), and motivational characteristics of weak FL readers in contrast to strong readers in 3 groups of L1 Finnish-speaking learners of English, aged 10, 14, and 17 years. This cross-sectional study covered a wide range of potential correlates, and therefore predictors, of FL reading based on previous research on reading in first, second (L2), and foreign languages. The weakest and strongest FL readers (1 standard deviation below or above the mean reading score) in each age group were selected for the comparisons reported in this article. The FL (English) skills other than reading were found to be the clearest distinguishing feature between weak and strong FL readers. However, L1 and cognitive skills in L1 and FL, as well as certain dimensions of motivation to use and learn the FL, were also found to separate the 2 reading groups. The implications of the findings for 2 different hypotheses about the nature of FL reading—the Threshold Hypothesis and the Linguistic Coding Differences Hypothesis—are discussed, as well as the implications for the diagnosis of strengths and weaknesses in reading in an FL.