Objectives To examine the prospective temporal stability of acute and transient psychotic disorders (ATPDs) and analyze whether there are clinical, psychopathological, or sociodemographic characteristics that predict ATPD diagnostic stability. Method We conducted a prospective, 2‐year, observational study of patients presenting a first‐episode ATPD. A multivariate logistic regression model was developed to identify independent variables associated with ATPD diagnostic stability. Well‐established predictive factors of diagnostic stability, as well as all the psychopathological features included in the ICD‐10 Diagnostic Criteria for Research (DCR) descriptions of ATPD, were analyzed. Results Sixty‐eight patients with a first episode of ATPD completed the study with a diagnostic stability rate as high as 55.9% (n = 38) at the end of the follow‐up period. Multivariate analysis revealed that diagnostic stability was independently significantly associated with the baseline presence of motility disturbances (OR = 6.86, 95% CI = 1.10–42.62; P = 0.039), the absence of hallucinations (OR = 5.75, 95% CI = 1.51–21.98; P = 0.010), and the absence of schizophrenic features (OR = 7.13, 95% CI = 1.38–36.90; P = 0.019). Conclusion A symptom checklist assessing these psychopathological features would enable early identification of those subjects whose initial ATPD diagnosis will remain stable over time.