This proposal addresses an important opportunity in the rapidly developing art of microfluidics. On one hand vast expertise is available on automation of single phase flows via microvalves or electrokinetics and on flow of drops on planar electrodes. These systems are perfectly suited for a range of applications but are inherently inefficient in handling massively large numbers of processes due to correspondingly large number of input/output controls that at best scales logarithmically in the number of processes. On the other hand conducting reactions in thousands micro droplets embodies many of the most acclaimed promises of microfluidics – ultra-miniaturisation, speed, rapid mixing and extensive control of physical conditions. Demonstrations of incubation of cells, in-vitro translation and directed evolution confirm that these techniques can reduce the cost and time of existing processes by orders of magnitude. Droplet microfluidics is at the moment, however, almost (except sorting) completely passive.We recently demonstrated the use of external valves to automate formation and motion of droplets on simple disposable chips and screening up to 10000 compositions per hour. We propose to develop externally controlled programmable modules for i) multiplexed, on-demand generation of multiple emulsions, ii) aspiration of libraries of samples and multiplexing linear libraries into full cross matrices, iii) splitting drops into two, few and large numbers (e.g. 10000) drops, iv) optical monitoring of presence and content of droplets, v) counting cells inside the drops, vi) circulating drops, vii) titration, viii) holding paramagnetic beads in drops. Our design rules will allow to integrate these modules into externally controlled systems for research on i) combinatorial synthesis, ii) material science, iii) role of noise in metabolic networks, iv) evolution of bacteria, v) inexpensive multiplexed diagnostics systems, including cytometry, PCR and ELISA assays in drops.