Relational values have recently emerged as a novel conceptfor research on human-environment relationships, seekingto understand ethical principles that may fosterenvironmental stewardship, coupled with a recognition ofnature’s contributions to people. At present, most empiricalresearch on relational values uses qualitative methods.Here we review some of the reasons that may havecontributed to the lack of quantitative research, besidesnoting that a lot of existing quantitative empirical researchon human-environment relationships already deals withrelational values, even if it does not use that terminology.We suggest that incorporating quantitative approaches intothe methodological toolkit of relational values research hasa number of benefits: First, it contributes to the empiricalevidence base testing hypotheses and assumptionsemerging from qualitative and conceptual work. Second, itmay help identifying core relational values shared acrosscultures, and this way improve communication andcooperation across different cultures. Third, it may improvethe political legitimacy of environmental decision-makingvia statistically representative measurements of publicviews. Complementing qualitative with quantitativeapproaches for relational values research is also in the spiritof integrated valuation and value pluralism.