This dissertation examines a cluster of texts centered on Hizakurige 膝栗毛, or Shank’s Mare, by Jippensha Ikku 十返舎一九 (1765-1831), the first eight installments of which were published annually between 1802 and 1809 in the city of Edo, now Tokyo. The series follows its ruffian protagonists Yajirobē 弥次郎兵衛 and Kitahachi 喜多八 on a picaresque journey, as they make their way down the Tōkaidō highway 東海道 (literally, “Eastern Seaboard Road”) on a largely spurious pilgrimage to the Grand Shrine at Ise. Hizakurige rapidly established Ikku as a major figure in the world of gesaku 戯作 (roughly, “vernacular popular writing”) at the turn of the 19th century, and remains one of the most famous, enduringly-popular pieces of gesaku ever written, known at least in passing to most people in contemporary Japan. Despite this, there has been no dissertation-length study of Hizakurige written in English until now. Accordingly, I investigate the roots of its immense popularity by examining the nuanced layers of laughter and enjoyment—or warai 笑い—that Yaji and Kita’s stories have brought to the readers of Hizakurige over the last two centuries. To do so, I explore a variety of sources, media, and genres that Jippensha Ikku drew upon to build the multifaceted and dynamic world of Hizakurige-related texts—or Hizakurigemono 膝栗毛物—with the groundbreaking first eight installments serving as the unifying nadir for my inquiries. I start with an in-depth introduction to Ikku’s life and his works, detailing his experiences as a writer, illustrator, playwright, poet, traveler, and, eventually, as a person with physical disabilities, which reveal much about the tone, style, and contents of Hizakurige. I examine scholarship on Ikku’s work has to date, and propose frameworks centered on the intertwined structural and compositional concepts of sekai 世界 (literally, “world”) and shukō 趣向 (roughly, “innovation”) in gesaku as conceptualized by Nakamura Yukihiko 中村幸彦 (1911-1998). The second chapter revolves around the role played by kyōka 狂歌 (comic poetry) in Ikku’s development as a creator of gesaku. Centered on two compilations of kyōka edited and illustrated by Ikku—Ikyoku suzukuregusa 夷曲十廻松 (Rustic Rhymes: Rustling in the Pines, 1799) and Ikyoku azuma nikki 夷曲東日記 (Rustic Rhymes: A Diary of Eastern Times, 1800)—the chapter makes use of a framework that hinges on shukō to analyze the structural and poetic techniques that kyōka poets had at their disposal to create meaning, develop narratives, and, ultimately, instill their poetry with wit and amusement. I take up the topic of Nansō kikō tabisuzuri 南総紀行旅眼石 (Travels to Nansō with a Glittering Ink-stone: The Gem-sights of the Journey, 1802) in the third chapter. Although it is an illustrated, kyōka-centric, two-protagonist travelogue written by Ikku in the same year as the first installment of Hizakurige, Tabisuzuri appears to have been a total flop. To discover why this might be, I examine the bibliographic and biographical context in which Tabisuzuri came to be written, explore how the poetically dense paratextual apparatus of its various prefaces function, and analyze a series of linked scenes from the main body of Tabisuzuri that are the direct progenitors for two of Hizakurige’s most infamous episodes. In the fourth chapter, I consider Hizakurige in the context of travel writing, beginning with the prefatory matter of Hizakurige, then discussing the influence of two groups of travel texts upon the development of Hizakurige: first, Chikusai 竹斎 (1621), by Toyama Dōya 富山道冶 (date of birth unknown -1634), and Tōkaidō meisho ki 東海道名所記 (Record of Famous Sites of the Tōkaidō, 1659), by Asai Ryōi浅井了意 (c. 1612-1691); and, second, a trio of illustrated guidebooks (Meisho zue 名所図会) written in 1780, 1796, and 1797 by Akisato Ritō 秋里離島 (fl. 1770-1830). In a comparative analysis, I show how the two-person protagonist structure of Hizakurige draws on models frequently seen in travel writing, and investigate how Yaji and Kita’s characterization is enlivened through their depiction both as equals and as lovers. I also investigate how and why Ikku makes increasingly extensive—but decreasingly innovative—use of motifs taken from the illustrations in Ritō’s Meisho zue series. Finally, in the fifth chapter I examine how Hizakurige is deeply influenced by shukō drawn from performative genres—particularly kyōgen—and how Hizakurige is imbued with a kind of “latent performativity” that offers a hybrid mode of engagement with the text that sits at the intersection between “reading” and “performing.” I contend that this latent performativity comes about through the operation of Hizakurige’s shukō, both as individual, discrete shukō that function in the context of a single moment of the text, and as more extended, structural “macro-shukō” that shape broader swaths of the text’s character and have a greater impact upon the development of Hizakurige’s sekai. Accordingly, I investigate how Ikku imitates and innovates upon shukō drawn from two kyōgen plays—Dobukacchiri どぶかっちり (“Kerplunk”) and Kitsunezuka 狐塚 (“Fox Mound”), exploring the key characteristics of these two kyōgen pieces, and carrying out comparative analyses of the relevant scenes in Hizakurige. Over the course of the dissertation, I attempt to offer a variety of answers to one central question: why does Hizakurige matter, and what is its significance for our understanding of the development of gesaku in the late Edo period (1603-1868)? I contend that Hizakurige is important not just because of its immediate success, or its subsequent influence on surrounding textual and dramatic genres, or its enduring popularity, but also because it demonstrates the need for a more fruitful approach for the study of early modern Japanese popular literature: one predicated not just on genre, but on the intertwined interactions of sekai and shukō.