We identify and assess the relative importance of the principal factors influencing the release of dissolved organic carbon (DOC) and dissolved forms of nitrogen (N) from a small upland headwater dominated by podzolic soils during a sequence of autumn runoff events. We achieve this by subjecting high-resolution hydrometeorological and hydrochemical data to an R-mode principal component factor analysis and a stepwise multivariate regression analysis. We find that the release of DOC and N is influenced by four principal factors, namely event magnitude, soil water flow through the Bs horizon, the length of time since the soil profile was last flushed, and rewetting of the H horizon. The release of DOC and dissolved organic nitrogen (DON) is most strongly influenced by the combination of event magnitude and soil water flow through the Bs horizon, and to a lesser extent by the length of time since the soil profile was last flushed. Rewetting of the H horizon also influences the release of DOC, but this is not the case for DON. The release of nitrate (NO3-N) is most strongly influenced by the combination of the length of time since the soil profile was last flushed and rewetting of the H horizon, and to a lesser extent by event magnitude. Soil water flow through the Bs horizon does not influence the release of NO3-N. We argue that the mechanisms by which the above factors influence the release of DOC and N are probably strongly associated with moisture-dependent biological activity, which governs the turnover of organic matter in the soil and limits the availability of NO3-N in the soil for leaching. We conclude that the release of DOC and N from upland headwaters dominated by podzolic soils is largely controlled by the variable interaction of hydrometeorological factors and moisture-dependent biological processes, and that a shift in climate towards drier summers and wetter winters may result in the release of DOC and N becoming increasingly variable and more episodic in the future. Copyright © 2006 John Wiley & Sons, Ltd.