Oviposition site choice, which is one of the most important forms of parental care in oviparous reptiles, has major effects on incubation duration, reproductive success, and offspring phenotype. We determined the thermal characteristics of nest-sites selected by females of the lacertid lizard Psammodromus algirus in laboratory thermal gradients, and we linked results with information on the effects of temperature on incubation times and hatchling phenotypes. Temperatures at oviposition sites (mean ± SD = 26.0 ± 1.9°C) were on average lower and had a lower variance than those at available sites (32.0 ± 6.2°C). The duration of incubation decreased dramatically as temperature increased. In fact, the hatching dates predicted by the temperatures selected in the thermogradients were delayed with respect to the mean emergence dates observed in the field. Such disparity might occur because (1) natural incubation temperatures are variable rather than constant, (2) they are expected to rise later in the season, and (3) temperatures that are too high can severely compromise embryonic survival. In addition, females might select relatively low nest-site temperatures because hatching too early can force juveniles to face limited growth opportunities caused by food shortage in the Mediterranean environments in which they live.