Distributions are widely used in reliability and survival analysis. In addition to the traditional distributions Weibull and Pareto distributions are having wide range of applications in the reliability. The purpose of this book is to give a brief introduction to those distributions with the emphasis on applications. After introducing the Weibull Pareto mixture distribution, the CLS distribution was developed. The CLS distribution plays a dominant role in the analysis and prediction of manpower models. It also explains the many other univariate platy kurtic and lepto kurtic distributions for different specific values of the parameters. It provides the distributional properties like mean, mode, median, variance, moments, characteristic function. The shapes of different frequency curve distributions, four central moments, explicit function and square of the distribution was derived. The book also includes the order statistics, Joint probability of order statistics. The extreme order statistics like maximum and minimum of a sample distribution were worked out. Application of these weibul pareto mixture distribution was given in this Book.