Mixtures of anionic direct dyes are used to achieve distinct color shades during dyeing of cellulose. Occasionally, the presence of bivalent alkaline-earth ions interferes with this dyeing process. A possible reason for this impairment is dyestuff aggregation. To investigate the aggregation process together with the resulting structure of the aggregates, time-resolved static light scattering was carried out with dilute solutions of a dyestuff mixture which contains 50 wt % of each component and which has an orange color shade. All scattering data of the aggregates could be interpreted consistently by means of the wormlike chain model. Comparatively short aggregates with a contour length of 250-300 nm were observed in the presence of Na2SO4 as an added salt. If the Na+ ions were exchanged by Mg2+ ions, a gradual increase of the aggregates was observed, extending over a time regime of several minutes and leading to contour lengths which were up to 10 times longer than those found in the presence of Na+ ions.