Corporate Social Responsibility (CSR) is embedded in the United Nations Sustainable Development Goals. This indicates the importance of the Social responsibility aspects of Highway construction contracts contributing to the decarbonisation agenda. Social Clauses and CSR in the Highway sector has little published literature. This study used a structured survey which collected data from all consultants and contractors who had been awarded Highway Construction Design and Construction contracts in Northern Ireland. Only one did not respond. The survey gathered both quantitative and qualitative data on the existing social clauses from a consultant and contractor perspective as this had not been examined previously. This study found that the Government Contractual Social Clauses were not considered to have a strong or very strong effect on decarbonisation. More work needs to be done to see how an increase in overall decarbonisation can be achieved through the clauses. The impact of adding additional clauses from the EU Green Deal should be considered and implemented alongside the existing clause elements in both Bulgaria and the United Kingdom. Differences in priorities from a consultant and contractor perspective were proven suggesting bespoke CSR clauses are needed for each. Case study examples show that there are many positive aspects of the clauses that need retained. CSR outputs can be strengthened through making existing models such as Building Research Establishment Environmental Assessment Method (BREEAM) or Project 13 contractual and workshops or meet the buyer events are proposed to increase knowledge of contractors of inbuilt social responsibilities..