Any of the SQL gurus out there have an opinion or two on the following code?

SELECT gsf1.*, classify.classcode, classify.classgrup ;
    FROM gsf1 ;
        LEFT JOIN classify ON gsf1.contactno = classify.contactno ;
            AND classify.classgrup = 'JOBTYPE'

It really bugs me to be joining on more than the keys, but if I don't do it this way, I have to do a separate select to restrict classify before joining the two results. Is this kosher?