Just like the well-known role of chirality in determining the materials properties of many industrial polymers, backbone stereochemistry could arguably have an important role in determining climate-relevant properties of atmospheric aerosols. Here, we hypothesize that surface activity may differ among stereoisomers, and that certain chiral oligomers may be more surface active than their monomeric precursors, some of which have already been shown to be considerably surface active on their own. This possibility is especially intriguing given that the enantiomeric ratio of chiral monoterpenes like α-pinene (i.e., the ratio of (-)-1 to (+)-1, Figure ) has been shown to be highly variable in the atmosphere and dependent on region, vegetation, temperature, time of day, and plant stress. Since surface activity is a major determinant of cloud activation through the lowering of the critical supersaturation required for cloud droplet activation, a link between molecular chirality and cloud activation could perhaps be thought of as a contributing factor in biosphere:atmosphere feedbacks like the ones elucidated for rainforest aerosols. Such a link may also help improve atmospheric models, which have been shown to underestimate cloud condensation nuclei production by as much as 30-50% in some cases if surfactants were excluded. There is little to no difference in gas-phase reactivity towards atmospheric oxidants between enantiomers of chiral biogenic volatile organic compounds, suggesting that once released into the atmosphere, (-)-and (+)-α-pinene react to form oxidation products at the same rate. For (-)-α-pinene [(-)-1], this process (Figure ) begins with an initial conversion to carbonyl-containing first-generation oxidation products such as pinonaldehyde (2), pinonic acid (3), hydroxy-pinonaldehyde (4), hydroxy-pinonic acid (5), and pinic acid (6). (+)-α-Pinene [(+)-1], on the other hand, affords the enantiomeric series of products (i.e., ent-2-6). The stereochemistry of the first-generation oxidation products is then retained in the subsequent aerosol particles, as has been shown for both α-pinene and isoprene derived SOA. While there has been some speculation as to the possible impacts of oligomer backbone stereochemistry on the physical properties and climate-relevant outcomes of SOA, quantitative experimental evidence has yet to be acquired using authentic standards. Furthermore, models often still consider the two separate enantiomers of biogenic volatile organic compounds as one species, disregarding the influence of compound stereochemistry on reactivity. If one draws the comparison of atmospheric oligomers to industrial polymers -whose physical properties depend on polymer tacticity and where controlling tacticity is therefore of paramount importance -the potential impact of oligomer stereochemistry on climate-relevant properties of atmospheric aerosols becomes apparent. For example, as depicted in Figure , dimerization and oligomerization of monomers derived from a single enantiomeric source (i.e., (-)-1 or (+)-1) leads to homochiral secondary organic material (SOM; the specific constituents within SOA) as shown for scenarios I and III (denoted as all blue or all red balls). The distribution of stereoisomers becomes more complex when mixtures of enantiomeric monomers are present, as seen in scenario II. Here, initial dimerization may lead to self-condensation (i.e., blue with blue or red with red) or may lead to crossed condensation between the two enantiomeric species to generate diastereomeric dimers of mixed chiral origin (i.e., blue with red). Subsequent accretion reactions may then proceed in either the same or opposite enantiomeric series, ultimately leading to a complex mixture of oligomers of mixed chiral origin. The relative rates of these stereochemical processes are, as far as we know, unknown at this time and no data exists regarding the physical properties of these stereochemically distinct species.