First Pacific-Asia Workshop on Web Mining andWeb-based Application 2008 is held in conjunction with Pacific-Asia Conference on Knowledge Discovery and Data Mining (PAKDD 2008). The Web represents a key driving force for a large spectrum of applications in which users interact with or within companies, organizations, governmental agencies, and educational or collaborative environments. User preferences and expectations, together with usage, content, and structural patterns obtained from the Web, form the basis for intelligent, personalized, and business-optimal services. Key Web business metrics enabled by proper data collection and processing are essential to run an effective business or service. Enabling technologies include data mining, scalable data warehousing and preprocessing, sequence discovery, real time processing, document classification, user modeling and evaluation models. Recipient technologies that demand for user profiling and usage patterns include recommendation systems, Web analytics applications, content management systems, and fraud or intrusion detection systems. The inherent and increasing heterogeneity of the Web has required Web-based applications to more effectively integrate a variety of types of data across multiple channels and from different sources. The development of techniques and architectures for more effective integration and mining of content, usage, and structure data from different sources is likely to lead to the next generation of more useful and more intelligent Web applications. The WMWA 2008 workshop aims to bring together practitioners and researchers from both academia and industry in order to foster the exchange of ideas and the dissemination of emerging solutions for intelligent Web-based applications and content mining. All accepted paper will be included in proceedings if they have paid for publishing fee, which will be published by IEEE Computer Society . All CPS conference publications are also submitted for indexing to EI's Engineering Information Index, Compendex, (Elsevier http://www.ei.org/), and ISI Thomson's Scientific and Technical Proceedings, ISTP/ISI Proceedings, and Current Contents on Diskette (ISI Thomson http://www.isinet.com/). IEEE conference publications are not indexed in ISI Thomson's Science Citation Index (SCI), a journal index, nor are they cited in ISI Thomson's Journal Citation Report (JCR). ISI Thomson does not currently index CD-ROMs, only print products.WMWA 2008 will be published by May, 2008 Outstanding papers will be included in a LNCS/LNAI Post Proceedings of PAKDD Workshops published by Springer after they have registrated and presented the paper in WMWA 2008. LNCS/LNAI Post Proceedings will be published by the end of November, 2008