Disclosed are new small molecules having a substituted quinazoline core structure and the uses thereof for modulating glucocerebrosidase activity. Also disclosed are pharmaceutical compositions comprising the small molecules or activated glucocerebrosidase conjugated to the small molecules, which compositions may be administered in methods of treating diseases or disorders associated with glucocerebrosidase activity, including neurological diseases and disorders such as Gaucher's disease and Parkinson's disease.