In the nascent field of human-nature relational values, there is a growing body of literature suggesting their transformative potential in sustainability education. The ability to analytically distinguish relational values from other valuations can both inform pedagogical approaches and help to identify how people understand and value their relationships with the living and more-than-living biospheric inhabitants. To address this need, an overarching question was posited: "Can a relational values-specific assessment instrument be designed and validated for use in post-secondary sustainability education?" Through a survey of the literature, thematic analysis of validated human-nature connection instruments, and multi-method qualitative research, a pilot instrument was developed and administered to sustainability professionals and post-secondary college students in the US and Canada. Statistical analysis and Cronbach's alpha confirmed construct validity and internal reliability, and the pilot instrument was further refined based on analysis of cognitive interviews and focus group data. The revised Human-Nature Relational Values (HNRV) assessment instrument, ready for additional validation, is appropriate for any adult English-speaking population to determine how and to what degree respondents experience relationality with nature. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]