This study concentrates on the theoretical and applied aspects of the contractual liability under the third parties act; the theoretical aspect of this liability includes the definition, conditions, the range, features, provisions, and legal basis. Additionally, the most important applications of this liability within Bahrain Civil Law is discussed: Construction contract, and Lease contract. The research defines contractual liability under the third party act as a contractual liability which will be held when the debtor uses a third party to implement his contractual commitments, as long as there are no contractual terms preventing this.