The “What Works” Research Brief No. 4 discusses the most recent evidence on the role of public works and workfare programmes in improving participants’ labour market and social outcomes. It draws from new knowledge on the effectiveness of these type of programmes summarized in the Synthesis Report “What works: Active Labour Market Policies in Latin America and the Caribbean” and the particular experience of the workfare programme Construyendo Perú implemented in Peru to improve employability and labour market outcomes of participants.