Within the diverse field of certification and licensure, millions of tests are administered each year by non-governmental bodies and state agencies. A perusal of relevant websites suggests that most of the major certification and licensure tests have associated sample items, practice tests and/or preparatory tests (prep tests) either in hard copy or online available to potential candidates. All three are described in the standards of the National Commission for Certifying Agencies (NCCA, 2016). Sample items are offered simply to give potential test candidates an idea of what items on the test may look like. Practice tests are made up of numerous sample items and may, in some instances, be constructed to match a test plan. Prep tests can be distinguished from practices tests on the basis that they are always constructed to match test specifications closely, and are used to provide candidates with a predicted score for the real test. While sample items are usually provided at no cost and prep tests have to be purchased, practice tests can either be offered for free (often by the organisation responsible for setting or administering the test1 ) or charged for by the entities that developed them (the certification/licencing authority2 or other organisations3). These distinctions are worth noting; however, for simplicity, the general term ‘practice tests’ is used in this paper to refer to various types of practice and preparation materials.