We discuss some features of the new logic programming language DALI for agents and multi-agent systems. In particular, we aim at illustrating the treatment of proactivity, which is based on the mechanism of the internal events. This mechanism is general and flexible, and it is different from all the other approaches that can be found in the literature. In this paper, as a case-study we discuss the design and implementation of an agent capable to perform simple forms of planning. In particular, we demonstrate how it is possible in DALI to perform STRIPS-like planning without implementing a meta-interpreter. In fact a DALI agent, which is capable of complex proactive behavior, can build stepby-step her plan by proactively checking for goals and possible actions.