Chén Sī 陳思 (fl. 1230s–1259), of Línān 臨安 (Hángzhōu), was a late-Southern-Sòng calligraphy connoisseur and bookseller — chéngzhōng láng 成忠郎 of the Jíxīdiàn Guóshǐ Shílùyuàn Mìshūshěng Sōufǎng 緝熙殿國史實錄院祕書省搜訪 (an imperial book-acquisition agent), as recorded in the colophon of his Xiǎo zì lù 小字錄. His Hǎitáng pǔ 海棠譜 self-preface dated Kāiqìng 1 (1259, jǐwèi) places him in the Lǐzōng era. His major works are: Bǎokè cóngbiān 寶刻叢編 KR2n0024 (Shàodìng 4 / 1231) — a jīnshí topical bibliography organised geographically; Shūyuàn jīnghuá 書苑菁華; Shū xiǎoshǐ 書小史; Hǎitáng pǔ; Xiǎo zì lù. The Sìkù catalogues several of these. He is often confused with Chén Sī of Tang (663–727, CBDB 140493) and other homonyms; CBDB 107942 records this Chén Sī but supplies no dates.