Primary language delay remains one of the most prevalent developmental delays in early childhood, particularly in disadvantaged areas. Previous research has established language difficulties and social disadvantage being particular risk factors for adverse outcomes later in life. To help prevent low educational achievement and poorer outcomes, early treatment for any speech and language problems is vital. Early intervention and parental involvement in treatment has proven beneficial for pre-school children experiencing language development difficulties. In areas where there is social disadvantage, however, parents often do not engage with treatment. A local service project has evaluated a new, joint-working intervention, Enhanced Parent-Based Intervention (EPBI), which took place in Children's Centres within areas of social disadvantage. This exploratory study compared the EPBI service with the existing standard parent-based intervention (PBI) and examined the effects on attendance, engagement with treatment and language outcomes for children. When the EPBI service was offered in the disadvantaged areas, take-up and attendance rates increased from 35% to 100% and from 50% to 80% respectively. Children made gains with their language development, and this progress was comparable with language gains made by children from standard PBI groups in areas without social disadvantage. The results of the service evaluation indicated that when parents engage with the intervention, EPBI resulted in positive outcomes for socially disadvantaged children, which could benefit society in the long-term with potential cost savings. Limitations and future developments are discussed.