"The CLT" usually refers to CLT's flagship college entrance exam, but the organization actually offers a family of related assessments for different grade levels. If you're planning ahead for a younger student, or just want to understand the full picture, here's how the three actually differ.
The flagship CLT
This is the college entrance exam -- built for high school juniors and seniors preparing to apply to college, and the direct alternative to the SAT and ACT accepted at hundreds of partner colleges. It's the version this site's practice question bank covers, and the one referenced in every other CLT article on this site unless otherwise noted. CLT releases the flagship exam in multiple numbered forms over time (used, for example, to rotate content across different administrations) -- if you come across a specific form referenced by number, it's still this same flagship college entrance exam.
Related: What to Expect on the CLT: Format, Scoring, and How to Prepare
CLT10
Designed for 9th and 10th graders, CLT10 functions as an alternative to the PSAT and the PreACT -- a way for younger students to get real practice with a college-entrance-style test format before they're actually applying to college, and to establish an early academic benchmark. It also serves as a genuine on-ramp to the flagship CLT later on, since it shares a similar format and question style, just calibrated for an earlier stage of a student's education. Notably, sophomores who take the CLT10 are eligible for a CLT10 National Award, a real scholarship opportunity tied to strong performance at that grade level.
CLT3-8
This is a separate assessment line built for 3rd through 8th grade students, assessing language arts and math skills appropriate to those younger grade levels. It's positioned as a diagnostic and grade-level benchmark tool -- helping students, parents, teachers, and school administrators track academic progress well before high school, rather than functioning as college-admissions-relevant testing in its own right.
How to decide which one fits your situation
If you're a current high school junior or senior preparing to apply to college, the flagship CLT is the one that matters for your applications -- that's what every other resource on this site is built around. If you're a parent or educator planning further ahead for a younger student, CLT10 is worth considering for 9th or 10th graders as an early benchmark and PSAT/PreACT alternative, while CLT3-8 is designed specifically for elementary and middle-school-aged assessment rather than college-admissions purposes. Check CLT's own current site for the most up-to-date details on registration and administration for whichever assessment actually fits your student's grade level, since offerings and policies can be updated over time.