The patterning of body-care behaviour in the Herring Gull has been studied by means of: (a) qualitative observations on four individuals, and (b) application of six quantitative analytical methods on the behaviour recordings of the dominant gull (which was least influenced by other individuals). The qualitative observations led to the conclusion that in a body-care sequence a number of sharp behaviour switches occur in a fixed order; between successive switches the following "main components" could occur: bathing, shaking, oiling, and preening. The quantitative methods with their results can be recapitulated as follows: 1. An analysis of frequencies of the different behaviour elements suggested that within the "main components" these frequencies tended to change gradually over time. 2. The distributions of the behaviour elements were further studied by means of the temporal relations between events of the same element. This analysis revealed that each element occurred in "bouts", which could be interspersed with events of other elements. 3. It was also studied whether different elements had similar distributions over the observation time. This method was concentrated on the behaviour during short intervals between events of the same element; its results indicated that different elements had different distributions over time, although these distributions could be partially overlapping. 4. The sequential patterning of these different frequency distributions was studied in detail by measuring the interval durations between events of different elements. The results of these four analytical methods could be explained by postulating a programme for sequencing and/or timing of smooth changes in the probabilities of occurrence of the different behaviour elements within each "main component". 5. By means of transition analysis it was investigated whether apart from the slow frequency changes, rapid processes also played a role. Because of differences between reciprocal transitions, it was concluded that those rapid processes were important too. 6. From the frequencies of the combinations between movements and the places to which they were directed, a certain amount of dependence between the components of separate behaviour events could be proved. The results of this study have been discussed in relation to Van lersel & Bol's study on preening in terns. It was argued that their threshold model was too simple for a satisfactory explanation of the patterning of body-care behaviour. The discussion of the present results in relation to hierachical models was more successful. The mechanism underlying body-care behaviour can be considered as a programme with a main routine (order of main components) and several sub-routines. The role of state variables in this programme has been illustrated in two diagrams.