International audienceThe extension of electricity, water and sanitation networks in developing cities seems to be a priori complicated by the deficiencies of urban planning. Nevertheless, on a daily basis, utility firms do install pipes and poles in unplanned settlements. The mechanisms they resort to in Delhi and Lima are here analysed as catalysts and revelators of an actually existing urbanism. Social, commercial and technical innovations help extend the coverage; institutional creativity and bricolage compensate for the inadequacy of the planning framework. The lack of planning of the built-up environment is actually not an obstacle to service extension; nonetheless, this process is suboptimal due to coordination deficits within the la...