The feasibility and utility of a self-administered treatment (workbook composed of Quality of Life Therapy activities, aimed at improving participants’ subjective quality of life (QoL), was investigated through a mixed (qualitative and quantitative) design. The results indicated the immediate treatment group did not improve immediately following their completion of the workbook, relative to a delayed treatment group; however, improvements to subjective QoL and negative mood were observed after a five- to six-week maintenance period. Further testing is warranted in order to verify whether these benefits were associated with engagement with the workbook. Qualitative results suggested most individuals found the workbook beneficial, but suggestions for improvement were noted. Given the cost-effectiveness and accessibility offered by self-administered treatments, further testing and project development is warranted in order to evaluate the empirical utility of this minimal therapist guidance, self-administered treatment aimed at improving the subjective well-being of individuals with average and lower subjective QoL on the Quality of Life Inventory. There is support for both positive psychology interventions in well-being and self-administered treatments; however, given the results of the current study, further orientation to the concept of subjective QoL may be necessary to facilitate adequate recruitment and foster potential benefits from workbook completion.