Constituting 5 % of the human genome, microRNAs represent a sizeable class of gene regulators that is predicted to control the expression of at least 60 % of all protein-coding RNAs. Dysregulation of microRNA function results in developmental defects and pathological diseases such as cancers and neurological disorders. Intriguingly, many phenotypes of microRNA deficiencies are subdued in normal condition but manifested apparently upon stress. Here, we outline experimental methods to monitor the level, targets, and activity of microRNAs as the first few steps to characterize how microRNA functions are altered upon stress.