Whereas the cross-sectional structure of schizophrenic symptoms has been studied extensively, little is known about the development of symptoms during acute episodes. In this study, symptom trajectories of 46 schizophrenia spectrum patients were examined based on daily observation during an average treatment period of 104 days. A novel time series approach was used to identify initial phases of response and other descriptive features of the trajectories. The results yielded five dynamical factors: (1) overall level of positive symptoms, (2) duration of nonspecific response, (3) slope of response in all symptom domains, (4) enduring negative symptoms, and (5) duration of response regarding psychoticity. Compared to patients with an acute schizophrenia-like psychotic disorder, schizophrenia and schizoaffective disorder patients ranked higher in factor 4 (enduring negative symptoms). They tended towards a lower level of positive symptoms and showed a less prominent response to treatment. The examination of a subsample of 19 patients with relapse indicated a prolonged duration of initial treatment response regarding psychoticity. The results support the validity of this approach for the description of symptom trajectories.