The typical alliance data, collected once early in therapy, or occasionally during therapy, are poorly suited for evaluating within-person processes [9]. Only repeated measures data allow for the proper disaggregation of between-person and withinperson effects [9,10]. When a set of measures is collected at a single point of time from multiple individuals, the resulting data provide information only about between-person relationships. In contrast, when a set of measures are collected at multiple points in time from multiple individuals, the resulting data contain information about both between-person and withinperson differences. Such data must be carefully specified to avoid confounding the two sources of variability.A disaggregation of the between-person and within-person variance components of a predictor not only allows the study of within-person processes separated from between-person effects, but also is able to examine cross-level interactions of betweenand within-person effects. For instance, the effect of reporting more alliance than expected for a particular patient may matter more for patients who have lower alliance in general. When the general (between-person) level of bond is low, for example when the patient has low trust that the therapist wants the best for him/her and is therefore preoccupied with this issue, a certain increase of this trust in a particular session might be a valued event with an immediate effect on symptoms. On the other hand, when the patient's trust is high already and not an issue for him/ her, the same increase would probably have less consequences.So far, the ability to separate these effects has not been fully capitalized upon in alliance research. Notable exceptions are the studies of Tasca and Lampard [1] and Falkenström et al.[2] and our own study Hoffart et al. [3]. The purpose of the present short communication is to present and discuss these studies, with particular emphasis on our own study.