Inclusion Criteria:

• Met diagnostic criteria for schizophrenia according to DSM IV (disorganized type [295.10], catatonic type [295.20], paranoid type [295.30], residual type [295.60] or undifferentiated type [295.90]) for at least 1 year before screening. Prior medical records, written documentation or verbal information obtained from previous psychiatric providers obtained by the investigator must be consistent with the diagnosis of schizophrenia
• A total PANSS score at screening of between 70 and 120, inclusive and at baseline of between 60 and 120, inclusive - Body mass index (BMI) i.e., [weight (kg)]/[height (m)]², of >17.0 kg/m2
• Women must be postmenopausal for at least 2 years, surgically sterile, abstinent, or agree to practice an effective method of birth control if they are sexually active before entry and throughout the study. Effective methods of birth control include: prescription hormonal contraceptives, intrauterine device, double-barrier method, and male partner sterilization. Women of childbearing potential must have a negative urine pregnancy test at baseline, before receiving a dose of study drug
• Is able and willing to meet or perform study requirements (e.g., answer self-administered questionnaires). If a patient is unable to read the questions, study personnel may read documents and the patient may then mark his or her choice
• Patients in the US must be able to understand spoken English to permit adequate ratings by the blinded central rater

Exclusion Criteria:

• Primary active DSM-IV Axis I diagnosis other than schizophrenia
• Patients who are unable to provide their own consent or who are currently involuntarily committed to psychiatric hospitalization
• DSM-IV diagnosis of active substance dependence within 3 months before the screening evaluation (nicotine and caffeine dependence are not exclusionary)
• History of treatment resistance as defined by failure to respond to 2 adequate studies of different antipsychotic medications
• An adequate study is defined as a minimum of 4 weeks at the patient's maximum tolerated dose
• Relevant history of or current presence of any significant or unstable cardiovascular, respiratory, neurological (including seizures or significant cerebrovascular), renal, hepatic, hematologic, endocrine, immunologic, morbid obesity (BMI>=40), or other systemic disease
• History of any severe preexisting gastrointestinal narrowing (pathologic or iatrogenic) or inability to swallow the oral tolerability medication whole with the aid of water for patients requiring oral tolerability testing
• Biochemistry, hematology or urinalysis test results that are not within the laboratory's normal reference range and are deemed to be clinically significant by the investigator
• History or evidence of clinically significant hepatic disease (including aspartate aminotransferase [AST] or alanine aminotransferase [ALT] >2 times the upper limit of normal) at screening
• History of neuroleptic malignant syndrome
• Significant risk of suicidal, homicidal or violent ideation or behavior as clinically assessed by the investigator
• History of life threatening allergic reaction to any drug
• Known or suspected hypersensitivity or intolerance of risperidone, paliperidone, Intralipid (placebo) or any of their excipients (e.g., soybean oil, egg yolks, phospholipids, glycerol)
• Exposure to an experimental drug, experimental biologic, or experimental medical device within 6 months before screening or prior randomization into this study
• Enrollment in 2 or more clinical research studies in the previous year or one or more clinical research studies in the previous 6 months (non intervention, observational, and retrospective studies excluded)
• History of any active malignancy within the previous 5 years, with the exception of excised basal cell carcinomas
• A woman who is pregnant, breast-feeding, or planning to become pregnant during the study period
• Employee of the investigator or study center, with direct involvement in the proposed study or other studies under the direction of that investigator or study center, as well as family members of the employees or the investigator
• Treatment with any of the following disallowed therapies: An injectable antipsychotic within 1 injection cycle before screening, An injection of RISPERDAL CONSTA within 6 weeks of screening, ECT within 60 days before screening, A previous injection of paliperidone palmitate within the past 10 months before baseline, Use of clozapine within 3 months before baseline, Nonselective or irreversible MAOI antidepressants within 30 days before screening: Other antidepressants unless patient has been on a stable dose for at least 30 days before screening (if less than 30 days and patient does not require the antidepressant it may be washed out before the baseline visit
• If less than 30 days and patient requires antidepressant treatment, the patient should not be included in the study), Mood stabilizers including lithium and all anticonvulsants are not allowed during the double-blind period, and also must be washed out by Day -1. The duration of the washout is up to the discretion of the investigator but in general should be 5 multiples of the elimination half-life. Beta-blockers, must be washed out by Day
• 1. The duration of the washout is up to the discretion of the investigator but in general should be 5 multiples of the elimination half-life. Beta blocker use can be re-initiated after randomization depending on clinical need. At each subsequent visit, the investigator should determine whether continuation of the beta-blocker is required. - History or presence of circumstances that may increase the risk of the occurrence of torsade de pointes and/or sudden death in association with the use of drugs that prolong the QTc interval, including:. HR < 50, Demonstration of repeated prolonged QTc Fridericia interval > 450 msec, as measured on more than one ECG (either during screening, or from prior medical record), The following cardiac conditions: sick sinus syndrome, complete AV block, congestive heart failure, polymorphic ventricular tachycardia, Clinically relevant hypocalcemia, hypokalemia or hypomagnesemia, Concomitant use of drugs that prolong the QTc interval (including Class 1A (e.g., quinidine, procainamide) or Class III (e.g., amiodarone, sotalol) antiarrhythmic medications)
• Presence of congenital prolongation of the QT interval