In certain embodiments, the invention provides methods and devices for assaying single particles in a population of particles, wherein at least two parameters are measured for each particle. One or more parameters can be measured while the particles are in the separate reaction volumes. Alternatively or in addition, one or more parameters can be measured in a later analytic step, e.g., where reactions are carried out in the separate reaction volumes and the reaction products are recovered and analyzed. In particular embodiments, one or more parameter measurements are carried out “in parallel,” i.e., essentially simultaneously in the separate reaction volumes.