Abstract: Pyrazole derivatives of Formula (Ia) and pharmaceutical compositions thereof that modulate the activity of the serotonin 5HT2A receptor. Formula (Ia). Compounds and pharmaceutical compositions thereof are directed to methods useful in the treatment of insomnia and related sleep disorders, platelet aggregation, coronary artery disease, myocardial infarction, transient ischemic attack, angina, stroke, atrial fibrillation, reducing the risk of blood clot formation, asthma or symptoms thereof, agitation or symptoms thereof, behavioral disorders, drug induced psychosis, excitative psychosis, Gilles de Ia Tourette's syndrome, manic disorder, organic or NOS psychosis, psychotic disorders, psychosis, acute schizophrenia, chronic schizophrenia, NOS schizophrenia and related disorders, diabetic-related disorders, progressive multifocal leukoencephalopathy and the like.