Small and medium-sized enterprises (SMEs) dominate the Single Market contributing to local employment generation and innovative supplies and services development. Yet, SMEs are continuously disproportionately underrepresented in public markets. On average EU member states spend approximately 14% of their gross domestic product (GDP) concluding public supplies, services and works contracts. EU rules aim to promote cross-border trade in the Single Market by removing the barriers faced by suppliers when tendering for public contracts. This research questions whether the inclusion of social criteria and innovative procedures facilitates SME participation in public contracts. The research questions what impact “the division of large contracts into small ‘lots’; the use of community benefit clauses; the use of subcontractor considerations; and the use of pre-commercial procurement (PCP) procedures” has on SME participation. A cross-border comparative case-study approach is adopted to examine the inclusion of social criteria and innovative procedures in four case studies. The case studies scrutinise the inclusion of social criteria in; a €1.7 billion works contract for the construction of a New Children’s Hospital in Ireland, a £27 million catering, cleaning and ancillary services contract conducted by Northern Ireland’s Central Procurement Directorate, and two PCP competitions conducted by Smart Dublin and Smart Belfast. The findings show how; the use of community benefit clauses and the use of lots facilitated a social enterprise in winning a proportion of a £27 million services and supplies contract; the use of subcontractor considerations resulted in the awarding of €500,000 of subcontracts to SMEs on a €1.7 billion contract within six months of contract commencement, and the use of PCP facilitated the participation of nine SMEs in public contracts. The thesis argues that public procurers should not to treat SMEs as a homogenised group and should design appropriate and proportionate policies for different forms of businesses, including social enterprises and innovative start-ups.