In the present chapter, acoustic (AE), electromagnetic (EME), and neutron (NE) emissions are measured during laboratory compression tests on natural rock specimens loaded up to failure. All the signals are acquired by a National Instruments Digitizer with eight channels simultaneously sampling. The main purpose is to give experimental evidence to the three different forms of energy emission from rocks under compression. The tests are performed on magnetite and basalt specimens at a constant displacement rate. AE signals are detected by applying to the specimen surface a piezoelectric (PZT) transducer with resonance frequency of about 150 kHz. EME signals are revealed by the current induced in a closed circuit by the change in the magnetic flux during specimen compression. The specimens are also monitored by means of a He3 proportional neutron detector. During the tests, the AE signals are firstly detected and then the EME. All the recorded signals are correlated to the load vs time diagrams. The EME signals are obtained, in particular, during the typical snap-back instabilities, which characterize the load versus displacement diagrams of brittle materials. Neutron emission signals are generally identified at the end of the tests. As a matter of fact, neutron bursts usually occur only when the behavior of the specimen in compression is particularly brittle. Applications of these monitoring techniques to earthquake forecasting will be proved to be possible in the Part V of this book, where we will see that the temporal sequence of the events results to be totally different from that of laboratory tests: first the neutron emission (one week before the earthquake), then the electromagnetic emission (3–4 days before the earthquake), and eventually the acoustic emission (one day before the earthquake).