The ability of middle and high school students to reason quantitatively within the context of environmental science was investigated. A quantitative reasoning (QR) learning progression was created with three progress variables: quantification act, quantitative interpretation, and quantitative modeling. An iterative research design was used as it is the standard method for the development of learning progressions. The learning progression was informed by interviews of 39 middle and high school students from 5 schools in the Western USA using QR assessments. To inform the lower anchor, intermediate levels, and upper anchor of achievement for the QR learning progression, an extensive review of the literature on QR was conducted. A learning progression framework was then hypothesized. To confirm the framework, three QR assessments within the context of environmental literacy were constructed. The interviews were conducted using these QR assessments. The results indicated that students do not actively engage in quantitative discourse without prompting and display a low level of QR ability. There were no consistent increases on the QR learning progression either across grade levels or across scales of micro/atomic, macro, and landscape.