In attempting to control vibration in structures it is desirable to be able to identify dominant paths of vibration transmission from sources (e.g. machines) through the structure to some point of interest. It is therefore necessary to be able to measure the vibration power flow at a point in a structure, possibly in the presence of large stationary wave amplitudes. By repeating measurements at many positions on a structure it should be possible to build up a pattern representing paths of significant power transmission. Several measurement methods have been investigated, both analytically and experimentally, to identify those most suitable for practical use. It has been shown that measurement dynamic range is the major limitation, and that this characteristic is governed by the instrumentation phase tolerances. Simplified methods have been shown to provide the best dynamic range coupled with acceptable accuracy in use. An electronic intensity meter, capable of narrow bandwidth measurements in real time, has been designed and constructed and results obtained on beam and plate type structures.