Drought plays a significant role in shaping tropical rainforest ecosystems, impacting their structure, biodiversity, and function. Although rainforests are known for their high levels of precipitation, periodic droughts have become more frequent and severe due to climate change, potentially having profound implications for these diverse and important ecosystems. Despite decades of climate-oriented research, much of our current understanding of climate impacts is limited to correlative and predictive analyses based on forest plot and climate grid data or shade house experiments on seedlings and saplings. A deeper understanding of how the ecosystem itself functions is necessary if we are to advance a mechanistic understanding of the ecosystem’s fundamental ecology and climate response.  In situ experiments are invaluable for understanding the complex effects of drought on rainforest ecosystems by allowing researchers to study the impacts directly within an environment where all interactions and feedback loops occur. Our research experiences range from plant-water relations to understanding the broader effects of drought on forest productivity and stand dynamics. Most critically, in situ studies enable researchers to observe how drought affects species interactions, such as those between plants, herbivores, and their predators. For example, by monitoring herbivory rates on drought-stressed plants, scientists can determine whether certain herbivores are more likely to feed on weakened plants, potentially leading to shifts in herbivore populations and predator-prey dynamics. Additionally, in situ experiments can help us understand how drought impacts decomposers, like termites, which are crucial for nutrient cycling. Reduced moisture can slow decomposition processes, affecting soil fertility and the availability of nutrients for plant growth. Ultimately, in situ experiments provide a comprehensive view of the cascading effects of drought, capturing the nuanced ways in which water scarcity impacts the entire ecosystem. This field-based approach yields ecologically relevant data that laboratory experiments and forest plot modelling cannot replicate, making it essential for predicting how tropical rainforests will respond to increasing drought frequencies and for developing effective conservation strategies to mitigate these impacts.