This is an open-label (all people know the identity of the intervention), prospective (study following participants forward in time), single arm, and non-comparative study of paliperidone Extended-release (ER) in participants switching from the previous oral antipsychotic to flexibly dosed paliperidone ER. The total study duration will be approximately of 24 weeks per participant. The study consists of 2 parts: Screening (that is, 14 days before study commences on Day 1); Treatment (24 weeks). Efficacy will primarily be evaluated by change from baseline in symptom checklist 90-R (SCL90-R) at Week 24. Participants' safety will be monitored throughout the study.