Background: Birth weight (BW) is often used as a proxy for gestational age (GA) in studies on preterm birth. Recent findings indicate that, in addition to perinatal outcomes, subjects born very preterm (VP; GA < 32 weeks) differ from those with a very low birth weight (VLBW; BW < 1,500 g) in postnatal growth up to their final height. Objective: To study whether neurodevelopmental and functional outcomes at the age of 19 years differ in VP and/or VLBW subjects. Methods: 705 19-year-old subjects from the Project on Preterm and Small-for-Gestational-Age Infants (POPS) cohort were classified as (1) VP+/VLBW+ (n = 354), (2) VP+/VLBW- (n = 144), or (3) VP-/VLBW+ (n = 207), and compared with regard to IQ as assessed with the Multicultural Capacity Test-intermediate level; neuromotor function using Touwen's examination of mild neurologic dysfunction; hearing loss; self- and parent-reported behavioral and emotional functioning; educational achievement and occupation; and self-assessed health using the Health Utilities Index and the London Handicap Scale. Results: VP+/VLBW- infants, on average, had 3.8-point higher IQ scores (95% confidence interval [CI] 0.5-7.1), a trend towards higher educational achievement, 3.3-dB better hearing (95% CI 1.2-5.4), and less anxious behavior, attention problems, and internalizing behavior than to VP+/VLBW+ subjects. VP-/VLBW+ infants reported 1.8 increased odds (95% CI 1.2-2.6) of poor health compared to VP+/VLBW+ subjects. Conclusions: At the age of 19 years, subjects born VP+/VLBW+, VP+/VLBW-, and VP-/VLBW+ have different neurodevelopmental and functional outcomes, although effect sizes are small. Hence, the terms VP and VLBW are not interchangeable. We recommend, at least for industrialized countries, to base inclusion in future studies on preterm populations on GA instead of on BW.