Selected afforestation and reforestation interventions have been studied in the Nainital district of Uttarakhand with the objectives to assess their carbon sequestration potential, and cost-effectiveness exclusive and inclusive of carbon benefits. The excel spreadsheet model “Project Based Comprehensive Mitigation Assessment Process” was employed to workout the annual incremental carbon sequestration, cost effectiveness indicators and likely benefits under different carbon price scenarios for each selected afforestation and reforestation intervention. The results have shown a wide range of sequestration potential, which varied from 0.19 tC/ha/yr in case of Plum block plantation to 4.81 tC/ha/yr for Pine block plantation, calculated for the assessment period 2008-38. The plantation interventions involving horticulture species demonstrated much lower carbon sequestration potential as compared to long rotation tree species, such as Oak and Pine. Among the selected plantation interventions Pine block, Mixed species block and Oak-Pine-mixed species block were observed to be associated with maximum carbon benefits, viz., Rs. 4060/ha/yr, Rs. 3370/ha/yr and Rs. 3112/ha/yr respectively. The study has demonstrated that plantation interventions involving long rotation tree species associated with recurring non-carbon benefits are more likely to succeed as afforestation and reforestation CDM project interventions compared to the horticulture species, associated with slower woody growth and limited carbon benefits.