The research entitled the Interference of Javanese Morphology and Syntax with Indonesian in the narrative essay at seventh grade students of SMP Negeri 1 Kalibagor aims to determine Javanese language interference in the form of morphology and syntax contained in several narrative essay of seventh grade students at SMP Negeri 1 Kalibagor. The research aims to provide information about the Javanese language especially on morphological and syntactic interference with Indonesian narrative essay of seventh grade students of SMP Negeri 1 Kalibagor. The data were in Indonesian sentences containing Javanese interference, both containing morphological interference dan syntactic interference, in narrative essays of seventh grade students at SMP Negeri 1 Kalibagor. The source of the research data is narrative essays of seventh grade students at SMP Negeri 1 Kalibagor. The data were collected by reading method namely reading students narrative essays and identifying linguistic forms containing interference. The data analysis phase used the intralingual equivalent method and then differencial comparison (HBB) technique. The presentation stage of the data in an informal way was to describe the result of the research that has ben obtained. Based on the results of the analysis, it can be concluded that the Javanese language morphological and syntactic interference contained in the students narrative essays be classified into several groups. Morphological interference in the Javanese language consists of two types, namely (1) morphological interference in the form of affixation and (2) morphological interference in the form of reduplication, while syntactic interference consists of five types, namely (1) interference type of construction phrase, (2) interference type of clause structure, (3) intrefrence of preposition use, (4) interference of conjuction use, and (5) interference of sentence structure