This paper investigatessound substitution and phonological processes in Izon, an Ijoid language spoken in Bayelsa, Delta, Edo, River, Ondo State and Cross River States in different Varieties. Using the Generative Phonology and Sociolinguistics Variationist theoretical frameworks, the study analyzes the changes that the Izon sounds undergo from the phonological form to the surface form. It examines how sound substitutions are socially motivated as a result of negative transfer. Data were gathered using checklist words containing the problematic phonemes. The findings show that substitution, deletion, insertion, contraction, and metathesis occur in Izon. The Process of Insertion takes place when Izon speakers add vowels to loan words in utterances to aid easy production of sounds, it occurs mostly at the initial and final positions of words and at other places to break off consonant clusters. Contraction occurs within the boundary when identical vowel occurs, while metathesis is seen in the substitution of sounds in loan words. This study adds significantly to materials available on Izon language in particular, and to phonology in general.