Methods for designing an assessment and providing accessibility features for a test taker profile are disclosed. A test taker profile, including multiple knowledge, skill and other attribute(s) (KSAs), is defined in which each KSA has a specific level. Each KSA is designated as either a focal KSA (an essential part of the targeted proficiency to be measured) or an ancillary KSA (not an essential part). For each focal KSA, a focal value (the value that the test taker must have to possess a high level in the targeted proficiency) is defined. For a particular test design alternative (which may include an accessibility feature), a requirement is determined for each KSA. An accessibility feature is selected which avoids indications of invalidity, including: a mismatch between the targeted proficiency and the expected proficiency; the test taker profile does not satisfy all ancillary requirements; and focal requirements are either excessive or insufficient.