var ContactModel = Backbone.Model.extend({ //extend Backbone.Model defaults: function(){ this.firstName = 'no first name yet'; this.lastName = 'no last name yet'; return this; } }); var contact1Model = new ContactModel( //instantiate model instance {firstName:'John'} ); // firstName is set to John while lastname remains the default value console.log(contact1Model.get('firstName')); //logs John console.log(contact1Model.get('lastName')); //logs 'no last name yet'