Long-term measurements in slice electrophysiology typically constitute long-term potentiation (LTP) and long- term depression (LTD). These measurements can last 1-2 h, requiring minimal baseline noise and easy detection of activated synaptic receptors. This can be relatively easy to achieve in fi eld recordings, but can be challenging in whole-cell confi gurations. In this chapter, we discuss the concepts behind LTP and LTD as well as the approaches that the beginning electrophysiologist can use in order to complete these long-term measurements. We fi nish with potential technical issues to consider during experimentation as well as suggestions that may increase the likelihood of successful recordings.