A preliminary contract is a legal instrument through which parties commit to entering into a principal contract under pre-agreed conditions. Should one party refuse to fulfill this obligation, the other party may seek a court order to compel the conclusion of the principal contract. In cases of refusal, the court’s decision can substitute for the contract itself. This paper examines the legal significance of preliminary contracts, the conditions for their validity, and the consequences arising from the breach of such obligations. The focus is on the distinction between pre-contractual and contractual liability. While pre-contractual liability pertains solely to the conduct of parties during negotiations, the non-fulfillment of obligations under a preliminary contract results in contractual liability for damages. For a preliminary contract to be legally valid, it must include all essential elements of the principal contract. Additionally, if the principal contract requires a specific form by law, the preliminary contract must be concluded in the same form. Special attention is given to the role of earnest money (deposit) as a security mechanism. If the party receiving the deposit fails to meet their obligations, the other party may claim a return of double the deposit. Conversely, if the party that provided the deposit is at fault, they forfeit their right to a return of the deposit. In conclusion, the preliminary contract is presented as a valuable legal mechanism that protects the interests of the contracting parties and reduces the risk of non-performance of contractual obligations, thereby contributing to the stability of contractual relationships.