In professional learning, just as in architecture, form follows function. Although professional learning designs are vitally important, they cannot be where we begin in our planning. Purpose -- our why -- must be our starting point in designing any professional learning experience. Educators who begin by attending to the questions, "What do we want to accomplish with students?" and "How will we know if we do?" will be better positioned to design meaningful change in their systems. As Stephen Covey (2004) reminds us, we must "begin with the end in mind." By following the simple, five-step process described here, derived from the five levels of evaluation, we can make professional learning more purposeful and far more effective. Thoughtful planning is the key to ensuring an effective link between teachers' professional learning and improvements in student learning.