The importance of pond technology is now recognized globally and indeed is undergoing a renaissance at the present time. It was therefore no surprise that scientists and engineers from over 25 countries presented their most recent findings at the Marrakech conference. The choice of Morocco was especially appropriate as it, like most countries of the Magreb, has actively endorsed and implemented the use of waste stabilization ponds as a preferred wastewater treatment technology. The need to reuse treated wastewater is a key component of the water cycle in such water-short regions, and the crucial role that ponds can play in the safe reuse of effluents, particularly for agriculture, has also been recognized and supported by active research at institutions all round the world. This issue contains a selection of the papers presented both in the oral and poster sessions at the conference and should prove very informative for those who wish to keep abreast of developments in the field. Among the 52 papers selected from the oral and poster sessions for these proceedings are work on the performance of ponds systems worldwide, pond microbiology, nutrient removal, pond sludges and sediments, pond design and modeling, high-rate ponds, and effluent reuse.