This thesis evaluated a new speech rhythm measure, the Lexical Judgement Task (LJT), by conducting a series of cross-sectional studies. It was examined whether the LJT could be used with children from different age groups, whether associations between speech rhythm sensitivity, phonological awareness and reading skills could be observed and whether speech rhythm sensitivity could predict reading skills cross-sectionally and longitudinally. Study 1 piloted the LJT with 5- to 9-year-old children and assessed the relationship between poor and good readers‟ speech rhythm sensitivity and their reading skills. Analyses showed that poor readers performed lower on the task compared to good readers, indicating that reduced stress sensitivity was related to lower reading proficiency. Examination of the task indicated potential fatigue effects, thus the task was shortened, which resulted in a 12-item tasks that was used through the remainder of the studies. Children between 4- and 11-years old were assessed in three following studies and results showed differential associations between stress sensitivity and reading (related) skills; indicating an involvement of maturation in stress sensitivity‟s development but also highlighting that stress sensitivity is involved in reading skills differently across varying ages. The final study in this thesis examined the longitudinal effect of stress sensitivity on reading skills and it was found that stress sensitivity was not able to account for growth in reading skills, independently from vocabulary or phonological processing skills; although concurrently unique variance in reading skills was accountable to stress sensitivity. Overall, this thesis highlights the importance of stress sensitivity in children‟s reading development, offers supporting evidence for previously found associations between this skills and reading abilities and demonstrates the need to incorporate speech rhythm sensitivity in theoretical reading development models.