In this paper we present how a cross impact matrix may be used in effects-based planning and effectsbased assessment for plan evaluation, plan refinement, generation of alternative plans, and subjective assessment of plans and plan elements. The purpose of using a cross impact matrix within the effectsbased planning process is to find inconsistencies and decisive influences within developed plans. The cross impact matrix represents the impact between all activities, supporting effects, decisive conditions, and military end state of the plan. We develop morphological methods for analyzing activities, evaluating and refining plans, and sensitivity based methods using Dempster-Shafer theory to find the decisive influences. For the effects-based assessment process we develop a method that takes subjective assessments regarding the activities of a plan as inputs. From these assessments and the cross impact matrix we calculate assessments for all other plan elements. The method is based on belief functions and their combination under a new generalization of the discounting operation. The methods are implemented in a Collaboration Synchronization Management Tool (CSMT).