The Radiated Tortoise (Astrochelys radiata) is one of Madagascar's four critically endangered tortoise species that has been heavily impacted by poaching. Despite successful captive breeding programs for this species, within Madagascar and internationally, little information is available detailing their reproductive ecology in the wild. In this study, I compare the characteristics of this species' reproduction and reproductive success in 1) a wild population (WP) within their natural habitat in Tsimanampetsotsa National Park, and 2) a captive population (CP) that is exposed to regional climatic conditions in southwest Madagascar. Breeding activities were seasonal, with egg depositions from February until October and mean (±SD) clutch sizes of 3.4 ± 1.6 eggs (CP) and 2.5 ± 0.5 eggs (WP). I found egg mass to be positively correlated with female body mass, and the CP tortoises were larger than in the WP. Egg masses in the CP (36.6 ± 6.4 g) were higher than in the WP (30.1 ± 4.0 g). Incubation time was between 132 and 271 d for the CP hatchlings, and incubation time in the WP was 210–292 d. Hatchlings from the CP emerged in December and January, whereas emergence was restricted to December in the WP. Hatchling body mass did not differ between the two populations. My results suggest that removing large individuals from wild populations (as a result of poaching pressure to support the local bush meat trade) may compromise the reproductive output and long-term survival of this species in the wild.