The paper tries to answer three questions from a Chilean perspective: what are public works concessions, why are they called “public-private partnerships” and what justifies them in Chile. To reach these objectives the author considers the Chilean, Spanish, Italian and Colombian law from where it is possible to conclude that public works concession contract is a public works contract with a special way of reimbursement. The paper studies the amendments introduced to Chilean Law by Act N.º20.410 of 2010. According to the author these amendments change the comprehension of the public works concessions contract and allow to name it as “public-private partnerships”. Finally, the author analyzes the arguments developed by legal and economy scholars to explain the rationale of these administrative contracts.