Methods for performing secure on-line testing without the need for pre-installation of a secure browser are provided. The methods use a general purpose web browser which is already installed on the user's computer and extend the browser so as to restrict the functionality of the user's computer in at least one way which makes the computer more secure with regard to testing. The extending occurs through the transmission of trusted code to the user's computer over the internet. The elimination of the need for pre-installation represents a major savings to school districts in terms of the amount of IT professional time that must be dedicated to on-line testing, especially for school districts having large numbers of installed computers. Apparatus for practicing the methods is also provided.