Most Australian education departments' gifted policies are guided by Gagne's Differentiated Model of Giftedness and Talent (DMGT; Gagne, 2003, 2004; 2008). In this examination and critique of the DMGT, an argument is made that the DMGT is based predominantly on behavioural/biological research, leaving out genuine environmental factors, and that its application relates specifically to gifted achievers. This renders gifted underachievers, including those who may have environmentally acquired socio-emotional problems (e.g., due to poor attachment and maternal depression), without a legitimate claim for identification or without an appropriate educational pathway. An expanded conception of underachievement is proposed, and a revised Model of Inclusive Gifted Identification and Progression (Wellisch and Brown, 2012) is reviewed and recommended as a replacement.