Purpose: Learning to read is a complex, multifaceted process that relies on several speech and language-related subskills. Individual differences in word reading outcomes are indicated among children with inaccurate speech sound productions, with some of these children developing later reading difficulties. There are inconsistent reports as to whether phonological deficits and/or weaknesses in oral language explain these subsequent reading difficulties. Thus, it remains unclear how variability in speech production accuracy in early childhood may impact reading development. Therefore, the present longitudinal study seeks to clarify the relation between speech sound production accuracy in kindergarten and subsequent reading outcomes with a focus on additional potential mediating factors. Method: Speech accuracy, core preliteracy skills (phonological awareness, rapid naming, and letter-name knowledge), and additional potential mediators (phonological memory and oral language abilities) were characterized at the start of formal reading instruction. Word reading, decoding, reading fluency, and comprehension were assessed at the end of second grade. Mediation analyses were conducted to examine factors that mediate the relation between speech accuracy in kindergarten and subsequent reading outcomes. Results: Initial associations between early speech sound production accuracy and subsequent reading outcomes were indicated; however, mediation effects of preliteracy skills (phonological awareness and letter-name knowledge) were identified for word reading, decoding, and reading fluency outcomes. For reading comprehension, mediation effects of preliteracy and vocabulary skills were observed. Conclusions: The relation between speech sound production accuracy and subsequent word reading, decoding, reading fluency, and comprehension was observed to be mediated by preliteracy skills, specifically phonological awareness and letter-name knowledge. For reading comprehension only, vocabulary knowledge were of additional importance.