This case report describes a young child with inconsistent phonological disorder (IPD). The child presented with unintelligible speech. She made limited progress on individual speech production goals targeting phonological patterns over 4 years, remaining unintelligible. The child was diagnosed with IPD following an inconsistency assessment and motor speech assessment. She completed 16 weeks of Core Vocabulary intervention to target phonological planning and consistency of word production. The child made significant gains in intelligibility once the Core Vocabulary intervention was initiated. This case report highlights the importance of identifying and providing appropriate intervention for IPD in young children.