Atmospheric aerosol particles consist of a highly complex mixture of thousands of different compounds. Mass spectrometric techniques are well suited for the analysis of these particles, with each method of analysis having specific advantages and disadvantages. On-line techniques offer high time resolution and thus allow for the investigation of rapidly changing signals. They typically measure either single particles or the average non-refractory submicrometer aerosol. Off-line techniques are often coupled to chromatography or another technique separating for a specific property, which enhances their resolving power. Ultra-high resolution mass spectrometry allows for an unambiguous assignment of the elemental composition throughout the majority of the mass range typically measured in ambient aerosol samples, i.e. up to about m/z 400-600. The quantitative determination of individual compounds, or of classes of compounds, remains an important, but often unresolved, topic. Examples of applications of various mass spectrometric techniques are presented, both from laboratory and field studies.