Book excerpt: Three papers in this dissertation are entirely self-contained. The papers are linked both through the methodologies used and through the issues addressed. Each of the paper seeks to understand the complexity effects of market design issues by using agent-based computational economic approach. The first essay addresses the question of which auction pricing rule should Treasury use that yields the highest revenue, especially whether the Treasury should use a discriminatory-price rule or a uniform-price one. Computational experiments are carefully designed based on four treatment factors: (1) the buyers' learning representation; (2) the number of buyers participating in the auction; (3) the total security demand capacity of buyers relative to the Treasury offered security supply (4) volatility of security prices in the secondary market. Key findings in this study show that Treasury revenue varies systematically with changes of treatments factor. The second essay tries to answer the question of what is the best bidding rule for multi-unit sealed-bid double auctions. Extending the earlier theoretical work which suggested that submitting supply offers in the form of price-quantity supply functions P(Q) will benefit the seller under one-sided auction with uncertain demand. However, this study results show that under double-sided multi-unit auction in which seller face a similar uncertain demand, submitting P(Q) supply offers not necessarily benefited sellers. Moreover, strategic interaction effects among players using P(Q) rules can lower sellers profit and overall market efficiency. Such insights are critical, especially to market designers who are concerned about the detailed aspects of market design implementation. The third essay addresses the experimental testing of the recently proposed wholesale power market design by Federal Energy Regulatory Commission. This Wholesale Power Market Platform (WPMP) is a complex market that requires market participants to simultaneously bid into real-time, day-ahead, ancillary, and transmission rights markets. The study main goals are to gain understanding the nature of this complex market design, at the same time to test whether WPMP design results in efficient, fair, robust market operations overtime, especially under conditions in which participants' strive to gain market power through strategic pricing, capacity withholding, and any other imaginable strategies.