Accredited by Sinta Rank 2 based on Ristekdikti No.10/E/KPT/2019 187 The Externality and Sustainable Development Priority of Cross Border Tourism * WERENFRIDUS TAENA, 1 MARCE SHERLY KASE, 1 FELISISIMA AFOAN *, 1 Universitas Timor, Kefamenanu, Indonesia Correspondance author: werentaena5@gmail.com * Article Article History Received: 27/01/2022 Reviewed: 24/03/2022 Accepted: 27/06/2022 Published: 27/06/2022 DOI: doi.org/10.29313/mimbar.v0i0.9 422` This work is licensed under a Creative Commons Attribution 4.0 International License Volume : 38 No. : 1 Month : June Year : 2022 Pages : 187-196 Abstract The purposes of this research are as follows: (1) analyze the externality of cross border tourism on sustainable development in Wini Subdistrict, Indonesia, (2) analyze priorities recommendations for sustainable cross border tourism development in Wini Indonesia. The study uses survey methods and data collections by means of observations and in-depth interviews with 20 respondents. Data analysis used is the Analytic Hierarchy Process (AHP) with three dimensions of development sustainability. This study finds that the externalities of developing cross-border tourism are economic (53.20%), social (31.20%), and ecological (15.60%). The economic externalities are positive, social externalities are divided into positive and negative, while environmental externalities are generally negative. The results of the analysis also recommend the development of the creative economy and investment in cross border tourism (52.20%), more professional and integrated tourism management between cross border tourism objects in Indonesia and Timor Leste (30.20%), and tourism development based on ecotourism (17.60%). Keywords: Cross Border Tourism; Externality; Sustainable Development @ 2022 Mimbar: Jurnal Sosial dan Pembangunan, Unisba Press. All rights reserved. Introduction Globalization has implications for the development of tourism, including tourism in border areas (Cross Border Tourism). Suwena K and Widyaatmaja IGN (2017) stated that the interrelationships between countries are the basis for planning the development of cross border tourism. Suartini NN and Utama MS (2013) define tourism development as a development activity related to the phenomenon of tourism to maximize resources in the form of capital, humans, and the nature of obtaining the maximum of tourism products namely goods and services. Tourism development can be operationalized in accordance with the results of the study by Bahiyah C et al (2018), namely infrastructure development and increasing tourist attractions to optimize tourism potential. The development of border tourism through the development of complete and quality infrastructure is a show of a country’s development (Sari UC and Rahman B, 2019). Wini as one of the main crossing gates from and to the Oecusse District of Republica Democtratica de Timor Leste (RDTL) country has a lot of potentials to be expanded as a cross border