NOVELTY - An isolated polypeptide having cellulolytic enhancing activity is new.    USE - The polypeptide is useful for degrading and fermenting a cellulosic material, for producing a fermentation product (all claimed), and for saccharifying the cellulosic material to fermentable sugars and to convert the fermentable sugars to useful fermentation products, e.g., fuel, potable ethanol, and/or platform chemicals (e.g., acids, alcohols, ketones, gases, and the like).    ADVANTAGE - New enzymes to increase efficiency and cost-effective enzyme solutions for saccharification of cellulosic material are provided.    DETAILED DESCRIPTION - An isolated polypeptide having cellulolytic enhancing activity is selected from (a) a polypeptide having at least 70%, e.g., at least 75-99%, or 100% sequence identity to the mature polypeptide of SEQ ID NO: 2; (b) a polypeptide encoded by a polynucleotide that hybridizes under at least medium-high stringency conditions with (i) the mature polypeptide coding sequence of SEQ ID NO: 1, (ii) its cDNA sequence, or (iii) the full-length complement of (i) or (ii); (c) a polypeptide encoded by a polynucleotide having at least 70%, e.g., at least 75-99%, or 100% sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 1; or its cDNA sequence; (d) a variant of the mature polypeptide of SEQ ID NO: 2 comprising a substitution, deletion, and/or insertion at one or more positions; and (e) a fragment of the polypeptide of (a), (b), (c), or (d) that has cellulolytic enhancing activity. Sequences are shown in Figure 1 in the specification. INDEPENDENT CLAIMS are:    (1) an isolated polynucleotide encoding the polypeptide above or encoding a signal peptide comprising or consisting of amino acids 1 to 22 of SEQ ID NO: 2;    (2) a method of producing the polypeptide above;    (3) a transgenic plant, plant part or plant cell transformed with a polynucleotide encoding the polypeptide above;    (4) a method of producing a mutant of a parent cell, by inactivating a polynucleotide encoding the polypeptide above, which results in the mutant producing less of the polypeptide than the parent cell;    (5) a whole broth formulation or cell culture composition comprising the polypeptide above;    (6) a process for degrading a cellulosic material, by treating the cellulosic material with an enzyme composition in the presence of the polypeptide having cellulolytic enhancing activity;    (7) a process for producing a fermentation product, by (a) saccharifying a cellulosic material with an enzyme composition in the presence of the polypeptide having cellulolytic enhancing activity, (b) fermenting the saccharified cellulosic material with one or more fermenting microorganisms to produce the fermentation product, and (c) recovering the fermentation product from the fermentation; and    (8) a process of fermenting a cellulosic material, by fermenting the cellulosic material with one or more fermenting microorganisms, where the cellulosic material is saccharified with an enzyme composition in the presence of the polypeptide having cellulolytic enhancing activity.