Measurement is a necessary prerequisite for software process improvement. However, few guidelines exist for systematic planning of measurement programs within software projects. We advocate beginning with goal-oriented measurement as expressed in the GQM paradigm. When applying GQM, meaningful refinement of measurement goals requires a deep understanding of the organization's software development processes. Software process modeling can act as a means to gain this understanding. We provide guidelines that state how software processes should be modeled in order to support the introduction of measurement in a software project. The process models are used to derive non-intrusive data collection procedures that satisfy the needs of multiple measurement goals and thereby minimize the data collection overhead. Finally, we present the lessons learned from jointly applying software process modeling and measurement technologies in two industrial software projects.