This chapter outlines the importance of lead management and its position within a B2B company. The well-known AIDA model provides the basic framework for understanding the complex customer journey of a potential customer, from prospect to purchase. The author provides an overview of the funnel concept, including all steps and their definitions as well as details about how these relate to marketing and sales. In addition, the chapter describes the peculiarities of B2B markets connected to the funnel concept. The transitions between the individual steps in the funnel mark important milestones of the customer journey and highlight the most critical KPIs. Successful lead management is only possible if the goals of the lead and marketing funnels are derived from sales goals. An organization is doomed to fail if the goals of these departments are not aligned. All aspects of lead management and the relationship between marketing and sales are summarized in the lead management maturity model (LMM). This model provides a framework for the evaluation and development of company organizations. This model allows an organization to assess and develop the ideal state in the collaboration of marketing, lead management, and sales.