Edward Cope's neo-Lamarckist theory operated with an alternative mechanism to natural selection. For him, increases or decreases of the ontogenic stages produce characteristics that could be generated and integrated into the organism through the inheritance of acquired characters. Increasing body complexity, or not, this mechanism increased adaptive capacity. This could be interpreted as biological progress in a manner similar to the interpretation made by proponents of synthetic evolutionary theory. But unlike the latter, neo-Lamarkism relegated natural selection to a secondary role. This study aims to clarify the position of Cope in relation to the phenomenon of biological progress, as well as his strongly adaptational approach, proposing that this has been an indirect contribution to the articulation of the new evolutionary synthesis.