This dissertation investigates the development of speech sound categories in infants with (FR) and without (NFR) a family risk of dyslexia. There were four research questions. The first was whether NFR infants would show evidence in favor of perceptual attunement. NFR infants aged 6-, 8- and 10 months were tested on their discrimination performance of a native (a:/ - /e:/) and non-native (English /ɛ/ - /æ) contrast. They showed evidence of discriminating the native contrast. For the non-native contrast, a decline in discrimination performance was found between the 6- and 8-month-old infants. These findings align with the theory of perceptual attunement. However, the 10-month-olds showed robust evidence of discriminating the non-native contrast. These findings show that the ability to discriminate a non-salient non-native contrast is not lost after the process of perceptual attunement has emerged. The results suggest that the performance of the infants depends on the applied experimental design, the age of the infants and the salience of the contrast. The second question focused on whether it was possible to classify individual NFR infants as (non-)discriminators. Infants’ discrimination performance of the native contrast was analyzed with a frequentist and Bayesian hierarchical approach. The latter approach was found to be a fruitful approach for individual classification. These findings call for assessment of individual discrimination in longitudinal studies and in studies that investigate the relation between early speech perception and later language or literacy skills to establish the true value of individual assessment. The third question investigated whether FR infants differed in their developmental discrimination trajectory from their NFR peers. Native (a:/ - /e:/) and non-native English (/ɛ/ - /æ/) speech perception was investigated in 6-, 8- and 10-month-old FR and NFR infants. Results were analyzed at the individual (Bayesian hierarchical modeling) and group level (frequentist modeling). Results of ...