MLIB is a MATLAB-based software package for the analysis of the spike data, ie shapes and temporal patterns of extracellularly recorded action potentials. In particular, MLIB contains functions for a) assessing spike sorting quality / unit isolation, and b) constructing all sorts of peri-stimulus time histograms as well as raster displays and spike density functions constructed with various filter kernels. The software package is accompanied by an extensive documentation, along with many examples using spike data from operantly conditioned, freely moving pigeons. The software can be downloaded from Matlab Central File Exchange.