This study investigated the development of working memory ability (measured by tasks assessing all four working memory components) from the end of kindergarten to the end of first grade--the first year reading is taught in school--and the relationship between working memory abilities in kindergarten and first grade and reading skills in first grade. A sample of 97 children who participated in Nevo and Breznitz's earlier study ["Journal of Experimental Child Psychology, 109" (2011) 73-90] were divided into two groups according to their decoding skills, resulting in 24 poor decoders and 73 typical decoders. The entire cohort improved significantly on all of the working memory measures from kindergarten to first grade, with the phonological complex memory at both time points showing the highest correlations with reading skills at first grade. However, there were differences found between the two decoding groups, with poor decoders exhibiting lower working memory abilities in most working memory measures, performing significantly lower on tests of all three reading skills (decoding, reading comprehension, and reading speed), and showing higher correlation coefficients between reading skills. Findings suggest that even before formal teaching of reading begins, it is important to reinforce working memory abilities in order to maximize future reading achievements. (Contains 6 tables.)