Software project development effort estimation is one of important activities in software project management.Accuracy in estimation is a challenge for software developers. There are a number of models that define a relationship between size and effort.Effort of developing a project increases with complexity of project but accuracy estimation are strongly required during early stages of project development. But data and information available at the starting phases of a project is not complete, not consistent and not even certain.Objective of this book is to develop a useful model that defines the software development life-cycle and estimates the effort of developing a software .This book uses Neuro-fuzzy,Use Case Point model, Artificial Neural Network ,Fuzzy logic, Modified Environmental and Revised Use Case Point to determine the effort early stage of the development based on Use Case diagram. Also it uses different training and learning functions to get the best result. The result shows that this model is the best out performing model for software effort estimation at early stage. This book is useful for software Engineering community and any computing fields.