Employing individuals marginalized in the labour market is of considerable significance both for those individuals and for the local self-government units within whose territory they reside. The legislator has provided for the possibility of applying social clauses as instruments to foster their em­ployment not only within social cooperatives of legal per­sons, but also within other entities operating on the local market. This article examines social clauses from the per­spective of their capacity to influence the structure and con­ditions of employment. Certain clauses enable an increase in the employment of marginalized persons by imposing an obligation on contractors to establish an employment rela­tionship, whereas others confer a degree of discretion upon contracting authorities by permitting the inclusion of appro­priate contractual provisions. The majority of the proposed regulatory solutions merit a positive assessment. Neverthe­less, in the authors’ opinion, further conceptual clarification within the relevant legal acts is required in order to enhance their effectiveness. By way of illustration, this applies to the specification of the categories of entities eligible to benefit from contracts reserved for groups of entities employing, in particular, marginalized persons. Furthermore, the leg­islator may consider introducing an illustrative catalogue of contractual control mechanisms to be incorporated into agreements concluded between contractors and contracting authorities, aimed at safeguarding the rights of employees engaged in the performance of such contracts.